Tech Droid

Download Videos from Youtube Trick

2012-01-12T09:25:00.000-08:00

First things first. Is it legal to download videos from Youtube?

As much I have understood from the Terms of Service, it's not a straight yes or no. Basically, Youtube doesn't have a publicly available API or service that would allow users to download the videos. Of course, you can download back the videos that you had originally uploaded. But who would do that anyway?

However, there are workarounds and tricks with which you can actually download any video from the website. There are many softwares/add-ons that easily do this job. Here is a snapshot from the published "Terms of Service".

You shall not download any Content unless you see a “download” or similar link displayed by YouTube on the Service for that Content. You shall not copy, reproduce, make available online or electronically transmit, publish, adapt, distribute, transmit, broadcast, display, sell, license, or otherwise exploit any Content for any other purposes without the prior written consent of YouTube or the respective licensors of the Content. YouTube and its licensors reserve all rights not expressly granted in and to the Service and the Content.

From Youtube Terms of Service

It says, that you cannot exploit the content/content-owners by selling the videos or re-distributing it, thereby, making a profit against your sales. That's obviously illegal for any kind of content, unless of course, the license makes that content freely re-distributable. So, if you download the videos using those workarounds and tricks, only for your personal use (ex, offline viewing), you probably aren't breaking any rules. What about those add-ons/softwares that do this? Well, it's not illegal for them, since they are just distributing the software. So, they are off the hook.

For personal use, it seems ok to download videos off from Youtube. So? let's see how hard or difficult it is to get this working.Actually, it's quite simple.

Step 1: You should have the VIDEO ID of the video that you want to download.

Step 2: You need to make a call to this api, to get the details for that video. The fmt parameter is for getting the specified format of the videos. See the "Quality and Codecs" section on this page on Wikipedia.

URL => http://www.youtube.com/get_video_info?video_id=VIDEO_ID&fmt=6

Step 3: Process the response. You will get a plain string response. That response contains all the direct URLs to various formats of the video. Look for the key "url_encoded_fmt_stream_map" and the value for this key is what you need from this response. You will need to filter out all the URLs from here, and get hold of the URL to the format you want to download. Here are some sample URLs.

http://o-o.preferred.bharti-bom1.v8.lscache7.c.youtube.com/videoplayback?sparams=id,expire,ip,ipbits,itag,source,ratebypass,cp&fexp=904510,914501,908302,902315,916201,905267&itag=45&ip=203.0.0.0&signature=095A9503E49931B0B849257048E73EB7388F515A.C13F4074ED92A82DF94BBD73E808E917369C224D&sver=3&ratebypass=yes&source=youtube&expire=1326412828&key=yt1&ipbits=8&cp=U0hRS1RMUF9HUkNOMV9MRlRJOjZ2TTNoOG9ialZD&id=c418f3a4b0f1b751&quality=hd720&fallback_host=tc.v8.cache7.c.youtube.com&type=video/webm; codecs="vp8.0, vorbis"&itag=45

http://o-o.preferred.bharti-bom1.v11.lscache3.c.youtube.com/videoplayback?sparams=id,expire,ip,ipbits,itag,source,ratebypass,cp&fexp=904510,914501,908302,902315,916201,905267&itag=22&ip=203.0.0.0&signature=2C46F096073FDACEFD3B4895EDBC3CA1162682AD.3BCAE9E76BBE98D3FB687AF16ECC595E35AD8173&sver=3&ratebypass=yes&source=youtube&expire=1326412828&key=yt1&ipbits=8&cp=U0hRS1RMUF9HUkNOMV9MRlRJOjZ2TTNoOG9ialZD&id=c418f3a4b0f1b751&quality=hd720&fallback_host=tc.v11.cache3.c.youtube.com&type=video/mp4; codecs="avc1.64001F, mp4a.40.2"&itag=22

If you notice the URLs, there is a type parameter, where you can determine which URL is for which format (type=video/mp4, type=video/webm etc).

Step 4: To finally be able to download the video, you need to strip off a few values from these URLs, just to make sure your calls don't fail due to long URLs. What I have noticed is that if you strip off (everything after the quality param) the last parts of the URLs, everything's just fine. So, the final URL would be something like:

http://o-o.preferred.bharti-bom1.v11.lscache3.c.youtube.com/videoplayback?sparams=id,expire,ip,ipbits,itag,source,ratebypass,cp&fexp=904510,914501,908302,902315,916201,905267&itag=22&ip=203.0.0.0&signature=2C46F096073FDACEFD3B4895EDBC3CA1162682AD.3BCAE9E76BBE98D3FB687AF16ECC595E35AD8173&sver=3&ratebypass=yes&source=youtube&expire=1326412828&key=yt1&ipbits=8&cp=U0hRS1RMUF9HUkNOMV9MRlRJOjZ2TTNoOG9ialZD&id=c418f3a4b0f1b751&quality=hd720

Step 5: Save the file with the proper extension. That's it. You are done.

If you ask how I got to know about this trick? Well, everything's already out there on the web. A lot of people have already blogged about it before. But, I had to dig for it for almost 2 days. So, I hope someone finds it useful. So, if you want to make your own Youtube Downloader, now you know "How to Download Youtube Videos programmatically".

Note: This method might stop working as and when Google/Youtube blocks this loophole. In the past, Youtube has been known to block a few other workarounds that had existed.

Bluetooth on Android : Part I

2011-12-28T10:17:00.000-08:00

This is a part of a series of posts in which I will put forward a full working app what uses bluetooth on your Android device to discover, connect, pair, send and receive files. The source code would be tagged with each part of this series.

Part 1: The app should be able to discover and list out the devices (paired/unpaired).

To start off with learning about bluetooth on Android, visit the official documentation. The documentation is quite lucid and clear. Here I will try to explain parts of my code.

The first activity (HomeActivity), for now, will have a single button "Discover Devices", which will take you to the activity(DiscoverDevicesActivity) where you can see the list of devices that are visible by your device.

This activity does a few things, quite a few if-else conditions.

First, you need to check if your device supports bluetooth. If you don't have the hardware capability on your phone, you won't be able to run this application. Eh!! Most of the phones would obviously have bluetooth. Ummm...Yes... But the emulators don't. Arrggghhh!!!!
Once you are sure that your device has bluetooth capability, the next thing to check if it is enabled or not. If it's enabled, move on to the next step, else you will need to turn it on first.

Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(intent, REQUEST_ENABLE_BT);

Once, you click on "Yes" on the confirmation dialog that you will see, bluetooth radio will be switched on for you. On the screen, the "Scan" button will become active. Once you tap the "Scan" button, the ListView will show the list of devices that your device can discover.

That's all for the first part of the series. But, there's a little more to understand abut discovery.

The process of discovery is asynchronous. The list view, currently shows two kinds of devices.

Devices which your phone already knows about (Paired)
Devices which are discovered (Which are not paired with your device)

Getting the already paired devices is simple. The BluetoothAdapter will give you details about such devices.

// Check already discovered devices
Set<BluetoothDevice> devices = bluetoothAdapter.getBondedDevices();
for (BluetoothDevice device : devices) {
adapter.addDevice(device);
}
adapter.notifyDataSetChanged();

Now comes the actual discovery part. For this, you will need to register a broadcast receiver which will be called whenever a new device is found. After registering the receiver, you need to trigger the discovery by calling the startDiscovery() method of the BluetoothAdapter.

// Scan for new devices
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(devicesReceiver, filter);

bluetoothAdapter.startDiscovery();

On the receiver's onReceive() method, we pick up the details about the new device found, and add it to our ListView.

public void onReceive(Context context, Intent intent) {
      String action = intent.getAction();
      // When discovery finds a device
      if (BluetoothDevice.ACTION_FOUND.equals(action)) {
      Log.i(TAG, "Device found");

          // Get the BluetoothDevice object from the Intent
          BluetoothDevice device = intent
                  .getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
          // Add the name and address to an array adapter to show in a ListView
          adapter.addDevice(device);
          adapter.notifyDataSetChanged();
}

The DevicesAdapter is a custom adapter for the ListView which we will be updating in the subsequent posts to show more information about the devices.

As always, you should unregister your receiver, once your activity is paused. Also, in addition to this, you should also cancel the discovery if at all you have started by calling the cancelDiscovery() method of the BluetoothAdapter.

The part 1 of the project can be checked out by fetching the source code and checking out the v1.0 tag from the repository. The complete source code can be found here.

Alternately, if you want to download the source of Part 1 as a zip, use this link to Part 1.

Drag and Drop (Honeycomb/ICS)

2011-10-31T15:33:00.000-07:00

Drag and drop is already available with Honeycomb and up. In this example, we will see how to implement a simple Drag and Drop Operation.

We have a ListView with some items. The other half of the screen would have a drop area which has a single TextView. We will see, how to drag items from the ListView, drop them into the drop area, which will update the TextView with the list item's title, and also, that particular item would be removed from the ListView.

We will trigger the drag operation, when you long tap on an item in the ListView. After the drag operation is started, you will see a floating view of the selected item, which you can move around the screen. When you approach the drop area, the background of the drop area would change, which means that you can now drop your item. Once you leave the item, the TextView inside the drop area will show the text of the selected item.

This should also work on Ice Cream Sandwich. You can find the whole source code here. The code is quite self-explanatory. But, if you have any queries, let me know through the comment form. There are a few comments in the code to help you.

Simple ViewPager for Android

2011-10-18T15:49:00.000-07:00

You would have seen many applications recently, which make use of the new and awesome ViewPager that allows views to be horizontally scrollable. The new Android Market app also implements a flavor of the ViewPager, although it's a little more complex that what we will see here. This class is not available directly for you to use. Check this blog for some insight. It would required you to download a compatibility library from Google, add it to your project wherever you would like to use it, and go about paging views.

And yes, it's very simple to implement. I have coded up a little sample where it shows you how to use a ViewPager with a simple PagerAdapter. More or less, it works like the ListViews. Although there is not much documentation for this, it's quite easy to set up everything.

Firstly, you would need to add the ViewPager into your layout file.

Listing of main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <TextView android:text="Page 1" android:id="@+id/textViewHeader"
        android:layout_width="fill_parent" android:layout_height="wrap_content"
        android:gravity="center" android:padding="10dip" android:textStyle="bold"></TextView>
    <android.support.v4.view.ViewPager
        android:layout_width="fill_parent" android:layout_height="fill_parent"
        android:id="@+id/viewPager" />
</LinearLayout>

In this sample, we are using an extra TextView which would show the current page you are on.

Setting up the ViewPager

ViewPager viewPager = (ViewPager) findViewById(R.id.viewPager);

MyPagerAdapter adapter = new MyPagerAdapter(this);
viewPager.setAdapter(adapter);

This code is almost identical to what we would do for a ListView or Gallery. The only difference is that the adapter here, extends a PagerAdapter instead.

The PagerAdapter

The PagerAdapter has a few methods that you would implement. For this example, I have four different views, one for each page. 2 are ListViews, a TextView and a Button, not in that order. Here are the methods that you would need to implement. Look at the MyPageAdapter class for more.

@Override

public void destroyItem(View view, int arg1, Object object) {

         ((ViewPager) view).removeView((View)object);

}

@Override

public int getCount() {
        return views.size();

}

@Override

public Object instantiateItem(View view, int position) {
           View view = views.get(position);
           ((ViewPager) view).addView(view);
           return view;

}

@Override

public boolean isViewFromObject(View view, Object object) {
           return view == object;
}

And you are done!!! Sweet.... You can find the whole source code here.

Automating Builds on Android - Part 2

2011-09-24T14:03:00.000-07:00

In the previous post, Automating Builds on Android - Part 1, we saw how to setup our projects to automate the build process. In this post, we will automate the process further to make Ant automatically use the passwords for our keystore and alias, label our builds to whatever name we like and put it in a specific location on your system (from where others can access it).

1. To make Ant use the passwords for our keystore automatically, we will create a separate properties file in our project folder where. Let's name it "passwords.properties". This file would contain two properties as listed below.

key.store.password=sample
key.alias.password=sample

2. We will need to make a small change in our build.xml file to tell Ant to load this property file while building. To do this, we simply add this one line in the build.xml file.

<property file="passwords.properties" />

If you try to run "ant release" command in your terminal, you will notice that Ant doesn't ask you to enter your passwords anymore. It has picked up the passwords from your passwords.properties file.

3. Adding a name and a time-stamp to your builds while making a release build needs a little more effort. We will now create another properties file called "extras.properties". This file would contain two more properties as listed below.

file_name_format=test_build_hello_world
build_location=C:/Builds/HelloWorld

The file_name_format would be used to name your output builds. Sometimes, you would want to name your builds differently based on whether it is a "daily_build" or "weekly_build" or a "release_build". Instead of renaming the output file manually, you could just change this property accordingly just before your type in "ant release", and your builds would automatically be named as you like. The other property, build_location is again a configurable value here, where Ant would put all your builds in the specified location. This could be a shared folder on your system from where anyone else can access it easily.

4. Now comes the lengthy part. To accommodate these changes in our build process, our original build.xml is not enough. We will have to tweak the actual underlying build.xml to make our build process more streamlined. Let's see how to do it. Pick up the build.xml from the sample project and replace the previous build.xml with this one. It will have a whole lot of Ant scripts. You don't have to worry about most of it, except for these lines.

<tstamp>
        <format property="time" pattern="dd_MMM" />
    </tstamp>
    <property file="local.properties" />
    <property file="passwords.properties" />
    <property file="extras.properties" />

Notice, that, we are using a time-stamp property which we would be using in our build.xml to version our builds based on the specific format. Our builds will be names as "test_build_hello_world_22_SEP.apk".

The last thing you need to change is this piece of code. You will find it somewhere in the new build.xml.

<property name="out.release.file.name" value="${file_name_format}_${time}.apk" />
<property name="out.release.file" location="${build_location}/${out.release.file.name}" />

5. Here, you can see that we have changed the property "out.release.file.name" to a value that we want the output file to be named as. And also, we changed the "out.release.file" to use our configured directory from the extras.properties file.

The final step is to run "ant release" for the last time, and you will see your final release build placed at your desired location.

You can find the sample project here.

Automating Builds on Android - Part 1

2011-09-24T13:14:00.000-07:00

Do you find it hard to get a release build of an Android app? Well, you could say that it's not at all difficult. It just takes about 1 minute to get a build, sign it with your release keys and you are done. For a typical moderately big Android app, you could have a QA process where you send out builds for testing or verification to someone else. And you could be sending out the builds multiple times a day. In such situations, it becomes a tad tedious getting release builds out of your eclipse. In this post, we will try to automate this process of preparing the release builds.

Our tool of choice is Ant. Most of you perhaps already know how to do set it up. We will, however, also see how to version or auto-label your builds in next post. In this post, we will go through the basics.

1. To start off with, create a "HelloWorldAnt" Android project.

2. The next step is to prepare our project to use Ant scripts. To do this, fire up your terminal, go to the directory where your project rests and type out this command.

android update project -p .

3. A few files would be added to your project. Among these, the build.xml is the file that Ant would read and package your apk.

Updated local.properties

Added file ./build.xml
Updated file ./proguard.cfg

4. Now try running this command in the terminal. After we setup everything, this is the one single command that we would run every time we need to create a release build.

ant release

5. You will see a long log of what Ant is doing. Look towards the end of the logs and you will notice these lines:

-release-nosign:

     [echo] No key.store and key.alias properties found in build.properties.

     [echo] Please sign /workspace/HelloWorldAnt/bin/HelloWorldAntActivity-unsigned.apk manually
     [echo] and run zipalign from the Android SDK tools.

6. So, till this point, the Ant tool has prepared an unsigned apk which it has kept in the bin folder of your project and it asks you to manually sign this apk with your release keys. Next step is to automate this process.

7. Put your keystore inside your project folder. For this project, sample_keystore is the keystore that we would be using to sign this application. Now, we need to tell Ant to use this keystore to sign our builds with. Here, we will add a few files to our project.

Filename: build.properties

File Listing:

key.store=sample_keystore
key.alias=samplekeystore

8. At this point, if you try running "ant release" command, it will ask you to enter the password for the keystore and the alias name, and finally, it would put the release and signed builds in your bin folder.

The next post will talk about customizing the build process to the next level.

Automating Builds on Android - Part 2

You can find the sample project here.

Flip animation in Android

2011-07-14T12:45:00.000-07:00

I love animations. Let's see the video first. If you are excited, go peek at the code.

In this example, the main layout contains two ImageView widgets with two different images that are to be animated. The image views actually overlapp each other, at first, but as the animation starts, only one of them is visible at a time, while the other is invisible.

For the animation, we are using a FlipAnimator class, which extends the Animation class. Here is how we need to initialize and setup the animation.

FlipAnimator animator = new FlipAnimator(imageViewOriginal, imageViewFlip,
imageViewFlip.getWidth() / 2, imageViewFlip.getHeight() / 2);
if (imageViewOriginal.getVisibility() == View.GONE) {
animator.reverse();
}
layout.startAnimation(animator);

There is a small check to tell the animator where to reverse the animation. This is not the perfect way, but you will get an idea. To initialize the animator, you will need to pass the original view and the flipped view and the x and y position of the axes about which it will be flipped.

The animator, internally uses a AccelerateDecelerateInterpolator.
"An interpolator where the rate of change starts and ends slowly but accelerates through the middle."

The main logic of the animation is written inside this method:
protected void applyTransformation(float interpolatedTime, Transformation t)

You can find the whole source code here.

References:
http://www.inter-fuser.com/2009/08/android-animations-3d-flip.html

Understanding Intents and Intent-Filters in Android

2011-07-10T12:35:00.000-07:00

Intents or Intent messaging is the Android’s way to pass messages/information to various components of Android. An Intent object contains information that the target component can act upon. Through Intents, your apps can trigger Activities, Services and Broadcast Receivers. The most common use of intents in any application is to directly launch an Activity or Service to perform action on the data being passed with the Intent object.

A sample use of Intent is shown in the following example.
1. To launch an Activity

Intent intent = new Intent(context, TagetActivity.class);
startActivity(intent);

2. To launch a Service

Intent intent = new Intent(context, TargetService.class);
startService(intent);

To pass some data within your intents you need pass them within the Intent object like this.

intent.put(key, value);

This way you can pass basic data-types that are supported by the Intent class. In these examples, we are specifying the component names explicitly, i.e, TagetActivity activity and TargetService service. These intents are examples of Explicit Intents wherein you specify the target component that you want to handle your data.

There would be situations where you would want the user to choose the target component, or to put in another way, the target component is determined dynamically at run-time depending on various factors. For an example, you would like to write a E-Mail app. The basic requirement would be that whenever a user clicks on an e-mail address, your app should be triggered, and it should be designed to capture the e-mail address that was clicked. This is where, Implicit Intents come into picture. Since, the e-mail address link that the user clicks on might not necessarily be a part of your application, you do not have the privilege of launching your Compose Activity on the click event of the link. What would you do in such a case?

What happens when the e-mail link is clicked?
When an email link is clicked, the app would create an Implicit Intent setting it up with the proper data and broadcast it. Something like this:

Intent intent = new Intent();
intent.setAction(Intent.ACTION_SEND);
intent.put(Intent.EXTRA_EMAIL, {email addresses}];
startActivity(intent);

In the above code snippet, we can see that the Intent here doesn’t specify the component name. However, it specifies an action and the list of email addresses. For this example, we just need to pass a string array with just one email address that the user has clicked on.

How would Android know which activity should be launched (or service for example). In such cases, Android tries to find the best match, i.e, the component that can handle such a payload. In case it finds multiple components, it gives the user a choice to make. For instance, if you have multiple email clients installed and all of them can handle such type of Intents, the user gets a list of all these apps (see image). He can then select one which would launch that particular component (Activity for this example). If it fails to find any components to handle this Intent, an exception will be thrown (ActivityNotFoundException in this case). Here we have two email applications that can handle this intent. The user is given a choice to select one of them when an e-mail link is clicked. Depending on the user’s choice, the corresponding activity will be launched.

How do we write an Activity that can handle such Intents?
We have to specify or rather design one of our activity, the compose screen of our email client that can handle such intents. For that, we need to specify Intent-Filters for this specific activity in the AndroidManifest.xml file.

<activity android:name=".ComposeActivity"
    android:label="@string/app_name">
    <intent-filter android:label="@string/app_name">
         <action android:name="android.intent.action.SEND" />
         <data android:scheme="mailto" />
         <category android:name="android.intent.category.DEFAULT"/>
    </intent-filter>
</activity>

The above code itself is self-explanatory. Your activity now can handle intents that are launched with this signature. The action is “android.intent.action.ACTION_SEND” and the data scheme is “mailto”, i.e, any email address. So, in your ComposeActivity, you can retrieve the email address list by querying the intent for the key, EXTRA_EMAIL and you will get the list of email addresses (one in this case). Typically, you will need to populate the Send To address field of your ComposeActivity now.

The intent resolution process tries to find a best match for the intent. Once it finds an Intent and launches the Activity with or without user interruption(in case multiple matches are found), the responsibility of handling the intent now lies with the target component. To finish off the article, here is the way to extract the email address that had been clicked.

Bundle data = getIntent().getExtras();
String[] emailAddresses = data.get(Intent.EXTRA_EMAIL);

The developer docs on Intent, Intent Filters and Intent Resolution mechanism is a nice read to understand the Intent mechanism of Android. You can find other examples of the types of data and schemes that you can design your apps for.

Custom title for your apps

2011-07-05T10:18:00.000-07:00

The default title bar for the apps might not suit the theme of your app. You also might want to add a few more things to the title bar which the default title bar doesn’t help you with. This example will help you develop your own Title Widget which you can directly embed in your layouts containing a left icon, a title text and a progress bar. You can also control the contents of these three widgets and change it as required in your activities. Here we go.

1. The first thing you should do is to switch off the default title. You can do this easily by specifying in your AndroidManifest.xml file that do not intend to use it.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.beanie.samples.titlewidget" android:versionCode="1"
   android:versionName="1.0">
   <application android:icon="@drawable/icon" android:label="@string/app_name"
       android:theme="@android:style/Theme.NoTitleBar">
       <activity android:name=".TitleWidgetActivity"
         android:label="@string/app_name">
       <intent-filter>
       <action android:name="android.intent.action.MAIN" />
       <category android:name="android.intent.category.LAUNCHER" />
       </intent-filter>
   </activity>
   </application>
   <uses-sdk android:minSdkVersion="4" />
</manifest>

Here, in the application tag, set the theme of your app to use the NoTitleBar theme.

2. Create a title_widget.xml which would be the custom layout for your title bar. You can technically add any number of widgets here and finally display it with your custom title. As an example, we will add an ImageView, a TextView and a ProgressBar here.

3. Create a TitleWidget.java class which extends LinearLayout(you can use any Layout) which loads this layout file and exposes methods to modify the contents of the widgets.

4. Add the TitleWidget class as the first view in all your activity layouts’ files to display your custom title bar.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
 xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical" android:layout_width="fill_parent"
 android:layout_height="fill_parent">
 <com.beanie.samples.titlewidget.TitleWidget
android:id="@+id/titleWidget"
  android:layout_width="fill_parent"
android:layout_height="wrap_content">
 </com.beanie.samples.titlewidget.TitleWidget>
</LinearLayout>

5. Now, in your activity, you can initialize this TitleWidget as any view, since it is a LinearLayout now, and can control the contents of all the widgets.

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // Initialize title Widget
        TitleWidget titleWidget = (TitleWidget)

                             findViewById(R.id.titleWidget);

        // Call the methods to change the underlying widgets
        titleWidget.setTitle("My Custom Title");
        titleWidget.setIcon(R.drawable.icon);
        titleWidget.showProgressBar();
        titleWidget.hideProgressBar();
    }

Now you have your own custom title. On the surface, it doesn’t actually feel like a title bar, and yes, it isn’t. It’s just a custom view, that you are trying to make it look like a title bar. Remember!! We switched off the titles by specifying that our app’s theme to “NoTitleBar”.
You can find the whole source code here.

Simple canvas-based Ball game

2011-06-24T03:42:00.000-07:00

This is a small project that does this.

"On your phone's screen, you will have a ball lying at the bottom part, in the middle. Once you touch any part of the screen, the ball starts moving in that direction. It continues to move till it hits one of the walls, bounces off the wall, and keeps moving. Depending on the point of touch, the ball will hit the left/right walls a few times, before it eventually escapes out of the view when it crosses the upper boundary."

Not super fancy stuff or algorithms. You can find the source code here.

Streaming Radio Stations on Android

2011-06-03T12:28:00.000-07:00

Streaming radio stations or audio files hosted on streaming servers on Android is pretty straight-forward. But then, Android has it's limitations. It won't stream just any file or radio station. In this post, I would not be specifying the formats or protocols that Android supports. Rather, this example is just a walk through of how the MediaPlayer class should be used to stream audio files/radio stations.

For an example here, I have used a SHOUTcast radio station. The URL for the source is:
http://shoutcast2.omroep.nl:8104/

The accompanying sample project contains a ProgressBar, two Buttons (for playing and stopping the MediaPlayer).

Before running the example, one should look into the documentation of the MediaPlayer class. A look at the state diagram would perhaps help you clear to understand how it actually works.

To initialize the MediaPlayer, you need a few lines of code. There you go:

MediaPlayer player = new MediaPlayer();
player.setDataSource("http://shoutcast2.omroep.nl:8104/");

Now that the MediaPlayer object is initialized, you are ready to start streaming. Ok, not actually. You will need to issue the MediaPlayer's prepare command. There are 2 variations of this.

prepare(): This is a synchronous call, which is blocked until the MediaPlayer object gets into the prepared state. This is okay if you are trying to play local files that would take the MediaPlayer longer, else your main thread will be blocked.
prepareAsync(): This is, as the name suggests, an asynchronous call. It returns immediately. But, that obvisouly, doesn't mean that the MediaPlayer is prepared yet. You will still have to wait for it to get into the prepared state, but since this method will not block your main thread, you can use this method when you are trying to stream some content from somewhere else. You will get a callback, when the MediaPlayer is ready through onPrepared(MediaPlayer mp) method, and then, the playing can start.

So, for our example, the best choice would be:

player.prepareAsync();

You need to attach a listener to the MediaPlayer to receive the callback when it is prepared. This is the code for that.

player.setOnPreparedListener(new OnPreparedListener(){

            public void onPrepared(MediaPlayer mp) {
                     player.start();
            }

});

Once, it goes into the prepared state, you can now start playing. Simple???? Yes, of course. Just to wrap it up, to stop the MediaPlayer, you need to call the stop() method.

There are several other helper methods which lets you query the progress or status of the player. Jump to the docs page and you will find more information on them. You can checkout the source code here.

Project source for the new Eclipse + Android tool chain. Download here.

NOTE: This sample project is tested on Gingerbread(2.3) and should work on Froyo(2.2) and above.

Sensors to Handle on Nexus S

2011-05-04T17:19:00.000-07:00

So many sensors to sense!!! Hmm, I don't yet know if there are appropriate APIs available yet on Gingerbread to access all these sensors. Got to read up now.

Using Custom fonts on Android

2011-04-08T15:07:00.000-07:00

I had to do this for a project that I am working on, and I felt that it wasn't possible to achieve this. Well, there are several examples on the internet regarding this and nothing seemed to be working for me. So, in this post, we will see how to use custom fonts for your application on Android.

Few things before we start off:

Not all fonts are compatible with Android
You need to package the ttf files with your apk
It's obviously a little bit of extra work

So for this example, we have a TextView and a Button with different fonts. To be able to use your custom font everywhere, ie, on all the TextView and Button widgets in your app, you will have to extend these classes to create your own TextView and Button classes. I have named them as MyTextView and MyButton. And then, I can use these buttons in my layout xml files, with the fully-qualified name of my custom classes.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">

    <com.beanie.samples.customfont.MyTextView
        android:layout_marginTop="10dip" android:id="@+id/textView"
        android:layout_width="fill_parent" android:layout_height="wrap_content"
        android:text="@string/hello" android:textSize="20sp"></com.beanie.samples.customfont.MyTextView>

    <com.beanie.samples.customfont.MyButton
        android:layout_marginTop="10dip" android:id="@+id/textView"
        android:layout_width="fill_parent" android:layout_height="wrap_content"
        android:text="@string/hello" android:textSize="20sp"></com.beanie.samples.customfont.MyButton>
</LinearLayout>

In both these classes, we have a method called init() which is called from all the constructors. The method is just 3 line long.

        if (!isInEditMode()) {
                  Typeface tf = Typeface.createFromAsset(getContext().getAssets(), "fonts/ds_digib.ttf");
                  setTypeface(tf);
        }

Simple!!! You might notice that there is an if condition. This is not required, but it does help when you are preparing your layouts on eclipse, and you need to keep checking if everything's fine. This method, isInEditMode() returns true while eclipses tries to render the view from the XML.

This is what the documentation says:

Indicates whether this View is currently in edit mode. A View is usually in edit mode when displayed within a developer tool. For instance, if this View is being drawn by a visual user interface builder, this method should return true. Subclasses should check the return value of this method to provide different behaviors if their normal behavior might interfere with the host environment. For instance: the class spawns a thread in its constructor, the drawing code relies on device-specific features, etc. This method is usually checked in the drawing code of custom widgets.

If you don't put this condition, the layout editor will complain about not being able to set the TypeFace. So, in the layout editor, you will see your TextView and Button widgets with the default font. But, when you run your app on an emulator or a device, you can see the goodness of your custom fonts.

The source code for the sample project can be found here. You can find 3 different fonts (ttf file) in the assets folder to play with.

Inverted Android Button

2011-04-03T14:34:00.000-07:00

Nothing complex. Just a few lines of code to invert your button. A horizontal flip of 180 degrees is pretty simple to achieve. If you want it with a specific angle, it might be a bit tricky.

Lets start with a creating a custom button class that extends the android Button class. Name it as InvertedButton.java.

You will need to override it's onDraw() method to rotate the canvas, so that before any drawing is done, you rotate it by 180 degrees. To make the text-alignment perfect, you will also need to do a few calculations.

    @Override
    protected void onDraw(Canvas canvas) {
        int left = getPaddingLeft();
        int top = getPaddingTop();
        int right = getPaddingRight();
        int bottom = getPaddingBottom();
        int width = getWidth() - left - right;
        int height = getHeight() - top - bottom;

        int saveCount = canvas.getSaveCount();
        canvas.translate(left + width / 2, top + height / 2);
        canvas.rotate(-180);
        canvas.translate((-width / 2)-left, (-height / 2)-top);
        canvas.restoreToCount(saveCount);

        super.onDraw(canvas);

    }

There you go. You can now add this button anywhere in your XML layouts and you will always get an inverted button.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <Button android:text="Button" android:id="@+id/button1"
        android:layout_width="wrap_content" android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal|top" android:textStyle="bold"></Button>
    <com.beanie.examples.invertedbutton.InvertedButton
        android:text="Button" android:id="@+id/button2" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:layout_gravity="center_horizontal|bottom"
        android:textStyle="bold"></com.beanie.examples.invertedbutton.InvertedButton>
</LinearLayout>

You can find the source code here. Happy coding!!!!

Websockets on Android

2011-03-26T00:24:00.000-07:00

Have you ever tried to use Websockets on Android? In a recent project that I have been working on, it was required to use WebSockets to build a native Android app. Why a native app? Well, the current webkit that ships with the Android devices is not as fast as we would have liked. So, we had to figure out a way to build a native app that would be able to connect through WebSockets.

There are quite a few libraries available out there. And it took a bit of time to figure out the best library available. Well, the library isn't that huge. The one that we finally decided to use had only 2 java files that got our work done. Simple, isn't it?

The link to the source is here. You just need these two files:
1. WebSocket.java
2. WebSocketFactory.java

Out of these two files, the main file that you would be working on is the WebSocket.java. The WebSocketFactory.java, is just an extension of the other class that gives you WebSocket instances, based one of the two Drafts (75/76) that you request for. I am using the Draft-76 of the implementation.

For our use, we didn't require the WebView portion embedded in the source. So we removed it.
This is how you instantiate and use a WebSocket.

WebSocket webSocket = new WebSocket(URI.create("ws://yourserver.com"), DRAFT-76, "any_id");
webSocket.connect();

After you connect to the server, there are different event callbacks that you could listen for.

onOpen() : This method will be called when the WebSocket is connected and ready for sending and receiving data.
onClose() : This method will be called when the connection is terminated.
onMessage() : This method will be called then a message is received over the socket.
onError() : This method is used to notify any error message that might occur. According to the project doc on github, this currently doesn't work properly.

When you need to send a message to the server, the WebSocket class has a send method which takes in a String as the message.

webSocket.send("Your message");

To know more about the project, visit anismiles' github project. Thanks anismiles. :)

Android Market on Emulator (2.2)

2011-01-12T12:32:00.000-08:00

It's been some time that I had tried getting the Market up and running on a 2.2 a.k.a Froyo emulator. On a previous post, I had described how to setup an emulator (1.5 and 1.6) with the Market app. Today, I got a comment on that post which points to a 2.2 image that does the same. You just have to download that image file and follow exactly the same steps to set it up.

This is the link to the system.img file. Thanks Anonymous for your contribution. I have tried this, and it works. Here's a link (David's Blog) that anonymous referred to. He has described all the steps to create this system image needed to put the Market app on emulator.

A few things:
- This image will only work on a 2.2 emulator
- While creating the emulator, you should specify the cache partition size as 96 MB.

Check out the previous post for more details.

There are however a few limitations that I found with this hack.

The Android Market app doesn't seem to update itself to the new UI that we currently have on our phones.
There are only a limited number of apps that show up on the Market. (No Angry Birds for example)

Improved Copy/Paste in Gingerbread

2010-12-16T01:05:00.000-08:00

It's really important for the copy/paste feature to work on a mobile even if you don't have a mouse to select text you want to copy. Apple's implementation is nice. Till Froyo, there wasn't a unified concept of copy/paste feature implemented. But, the Gingerbread has actually changed a few things :) . Copying phone numbers from your mails and email addresses from web pages should be trivial and should involve the least amount of button presses. Prior to Gingerbread, this wasn't the case, but Gingerbread has this "New Feature now".

Here's the link where you can find out more about this.

Some images and videos

Official documentation

You need to double-tap on the text before you can bring up the text selection controls. Once you are done with the selection, single tap on the text copies the selected text to the clipboard, and then you can extract the data from the clipboard. This is really nice. Else, you would have to write a bit of extra code to trigger text selection mode first. This copy/paste selector works on an EditText and on the Browser. I haven't tested it further.

Gingerbread Stuff!!!! **It works on the emulator**.

Getting animations to work

2010-11-16T12:30:00.000-08:00

This is a simple project that will explain how to use animations in android through AnimationDrawable. The documentation was a bit outdated. But you might hit a dead-end if you try to call the animation's start method from within any of the Activity's life-cycle methods.

In this example, there is an ImageView with it's "src" value set to an image. The ImageView's background is set with you own AnimationDrawable, basically an xml in your res/drawable folder. In the activity, the ImageView has a click listener, which creates an AnimationDrawable from the ImageView's background, and just calls the start method of the AnimationDrawable class.

Here is a sample AnimationDrawable described through XML.

<?xml version="1.0" encoding="utf-8"?>
<animation-list xmlns:android="http://schemas.android.com/apk/res/android"
    android:oneshot="false">
    <item android:drawable="@drawable/black" android:duration="200" />
    <item android:drawable="@drawable/cyan" android:duration="200" />
    <item android:drawable="@drawable/green" android:duration="200" />
    <item android:drawable="@drawable/magenta" android:duration="200" />
    <item android:drawable="@drawable/navy" android:duration="200" />
    <item android:drawable="@drawable/orange" android:duration="200" />
    <item android:drawable="@drawable/pink" android:duration="200" />
    <item android:drawable="@drawable/white" android:duration="200" />
    <item android:drawable="@drawable/yellow" android:duration="200" />
</animation-list>

And here is the code that gets your animation started.

imageView = (ImageView) findViewById(R.id.ImageButton01);
        imageView.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                AnimationDrawable animator = (AnimationDrawable) imageView.getBackground();
                imageView.setImageDrawable(null);
                animator.start();
            }
        });

One point to notice is that, you have to remove the ImageView's "src" value, so that the animation is visible, since the animation works by changing the background of the ImageView, else, your animation would be blocked by the ImageView's "src" image.

Once you are done, you can stop the animation, and reset the ImageView's "src" to it's original image.

// Call this method to stop the animation
    public void stopAnimation(){
        AnimationDrawable animator = (AnimationDrawable) imageView.getBackground();
        animator.stop();
        imageView.setImageResource(R.drawable.icon);
    }

You can find the whole source code for this example here.

Unzip files in Android

2010-10-24T15:13:00.000-07:00

You need an app that can unzip files? Android provides the classes that are required for this. Basically you will need to checkout two classes. There are other related classes also which would help you with various other things.

This example shows you how to unzip a zip file through these classes. If you want to create zip files, that's also possible, but we will keep it for later. In this project, there is a zip file, called ZipTest.zip in the assets folder. It's pretty easy to pick up any zip file on your phone through code. For simplicity, I have placed out test file in the assets folder.

The code is simple enough to need any more explanations. I have put comments in the code. So, do check it out and run it. I have logged the steps on the Activity. ~~The output files are not readable yet in this example due to the format of writing that I have done here~~ (Update: As per rekin's comment, this is fixed now). But you get idea about how to unzip those files. You can find the whole working code here.

Note: There's not much error handling code put in place.

Android WebView, Javascript and CSS

2010-10-19T13:22:00.000-07:00

Using WebViews on Android is pretty interesting. I have come across some situations where I had to use a WebView to display some HTML content. Displaying HTML content is pretty straight-forward. But when it comes to controlling the web view, it gets a little complex. Things like showing alerts, manipulating divs and controlling the activity (closing/finishing). This example shows a few techniques that will get you going with Javascript and CSS with WebView.

1. CSS: Applying CSS is just the same as you would do with normal HTML pages. The sample_page.html in the assets folder refers to the sample_style.css file in the same folder. One thing you might notice is how we get the rounder corners for the divs. This CSS attribute does the trick.

-webkit-border-radius: 5px;

2. Javascript: To make it simpler, I have used the JQuery library. The mobile version released recently gave some errors. So, I have used the normal library available. The jquery-1.4.2.min.js also resides in the assets folder and is referenced in the sample_page.html.

3. All together: In the sample_page.html I have a header, a body and the controls. The controls have four buttons
      a: JToggle: This toggles the visibility of the body section. This is a pure javascript method call from the html.
      b: NToggle: This also toggles the visibility of the body section. But it does it differently. The javascript calls to the JSInterface.java method, which in turn calls the same Javascript method.
      c. Exit: This button basically closes/exits the app, by calling the JSInterface.java method which is bound to the HomeActivity.java via OnExitAppListener.java
      d. Alert: This shows an alert which is basically an AlertDialog in Android.

Calling a Javascript method from your Java code:
webView.loadUrl("javascript:jsToggle()");

Calling a Java method from Javascript:
window.jsinterface.nativeToggle();
/*
// Before using the above code, you have to inject the interface object which
// has a name "jsinterface"
webView.addJavascriptInterface(jsInterface, "jsinterface");
*/

Controlling the Alerts from Javascript:
The SampleChromeClient.java which extends the WebChromeClient has several methods which provide hooks which allow you to customize their behaviour. For an example, you can override the behaviour of the alert function and do whatever you want. You can show your own dialog with Yes/No buttons and depending on the input, you can send back the result to your Javascript code.
@Override
public boolean onJsAlert(WebView view, String url, String message, JsResult result)
{
     url = "Sample App Alert";
     return super.onJsAlert(view, url, message, result);
}
You can checkout the whole source code here. It's ready to run. Let me know if you have any issues.

More security for your Android

2010-10-15T04:49:00.000-07:00

Android has been criticized by a few of not having stricter security policies, on which a user could count on if his device is lost or stolen. Since more and more data, both personal and confidential are finding there way into our smart phones, we do need a more secure system to ensure that our data never fall into the wrong hands. Well, with Android 2.2(Froyo), your Android phones can be more secure by using the new Device Administration API.

What could this API do?
Using these APIs, the IT-Admins can install a Admin App, which enforces system wide security policies.

- Enable Passwords (Only lock screen as of now)
- Set minimum password length
- Alphanumeric password required
- Maximum password attempts
- Maximum inactivity time lock
- Lock device immediately
- Wipe the device data (to factory settings) (Remote/Local)

The key to all these features are that you have to have that admin app installed and activated as well. Also, you can have multiple admin apps that enforce multiple security policies. In situations of clash, the most strict policy will be enforced. This admin app controls how your device behaves in different situations. You can set parameters as to when and under what conditions your device should be wiped out. Say, after 20 failed password attempts, you want to wipe out the data to factory settings, the Admin app can do this using the Device Administration API.

For more information and samples on how to start with this API, visit the official documentation here.

With more and more features being packed into Android, now it is probably targeting the enterprises. Not having a way of enforcing such policies have indeed been a setback for Android to entice the Business users, but now, I can hear them come running. :D

ExpandableListView on Android

2010-09-16T15:01:00.000-07:00

ListView is pretty widely used. There are situations when you would like to group/categorize your list items. To achieve such a thing on Android, you would probably use the ExpandableListView. The data to the ExpandableListView is supplied by a special kind of adapter called the SimpleExpandableListAdapter which extends the BaseExpandableListAdapter.

As with any other widget on Android, you are free to customize the widgets as per your needs. Here, I will show how to create such a custom list adapter for the ExpandableListView.

For this example, I want to show a list of vehicles with their names. Also, I want to group them according to their category.

I have 4 classes.
1. Vehicle : The parent class for the rest.
2. Car: Extends the Vehicle class.
3. Bus: Extends the Vehicle class.
4. Bike: Extends the Vehicle class.

I have a method called getRandomVehicle(String name) which returns a random vehicle instance setting the name that I pass. The vehicle can be a Bus, Car or a Bike. Its completely random.

In the ExpandableListAdapter, (the custom adapter), there's a method called addItem(Vehicle vehicle), which manages the groups and their children.

In the SampleActivity, I have initialized a blank ExpandableListAdapter and set it to the list view. Now, I start a thread, which gets a random vehicle after every 2 seconds, and adds it to the adapter, and calls the adapter to notify that the data has changed.

There are a few methods, in the ExpandableListAdapter, which you should go through carefully. I have two layout files, group_layout.xml and child_layout.xml which are used as the layout for the group views and the child views of the ExpandableListView.

There you go, you have a custom ExpandableListView. You can find the full source code for this example here, ready to run.

There are some more methods that you might be interested in, like, how to change the "arrow icon" for the group views(official doc link), or how to expand or collapse a group at will, or how to handle specific events like group collapsed or group expanded. Read the docs on ExpandableListView.

SDK Tools - ADT Plugin updated

2010-09-12T15:22:00.000-07:00

Here comes a new update to the ADT plugin for eclipse and SDK tools.

After you update the SDK tools(r7) from the Android SDK manager or otherwise, you would be prompted to update the ADT plugin(0.9.8) as well. Go for it, and you will see quite a few changes.

In the SDK Tools:
http://developer.android.com/sdk/tools-notes.html

In the ADT Plugin:
http://developer.android.com/sdk/eclipse-adt.html

For SDK Tools
- Support for library projects.
- Support for aidl files in library projects
- Support for extension targets in Ant build to perform tasks between the normal tasks
- Support for "headless" SDK update
- Fixes location control in DDMS to work in any locale not using '.' as a decimal point

For ADT Plugin
- Rename package : One click change of project's package
- Support for library projects that don't have a source folder called src/
- Support for library projects that depend on other library projects
- Support for additional resource qualifiers: car/desk, night/notnight and navexposed/navhidden
- Adds more device screen types in the layout editor. (Nice)
- Fixes problems with handling of library project names

The most important update for me is the inclusion of more layout editor configurations by default. My last post on creating different configurations for different screen sizes here was just an example to create a configuration for working with different screen sizes at design time. It's a bonus that they are now included in there by default.

Once click package renaming is also a nice feature, in case you want to fork your project into different versions. Check them out.

Getting started with Tablets - They are coming

2010-09-04T17:34:00.000-07:00

So, Android phones are done. Now's the time to give the iPads a rest. If you would like to develop applications for Android Tablets, you need to get a few things up first.

First of all, you need to setup a few tablet emulators for your apps. This bit is rather simple. Create a new AVD. I guess this screenshot explains the rest. For some reasons, I have not been able to create Tablet AVDs on 1.6. But it definitely works on Android 2.2 (Froyo).

After you create this AVD, fire it up. And you should be able to see the Droid up and jumping.

You can now test out your apps on this tablet emulator. Well, since tablet devices will obviously come under large-screens, to make your designing layouts for large screens easy, you need to tweak up a few things on eclipse. Since, large screen devices take up the xml layouts from the "layout-large" and "layout-large-land" folders, if it all you have different layouts for large screens, to visualize your designs during your development, you need to add one more configuration for large screens.

Steps to add a new configuration

- Open eclipse. Open any layout xml, so that you can get to the screen where you can add a custom configuration.

- In the devices drop down, select custom to create a new configuration. Click on "Create" which will open up the configuration screen.

- On the new configuration screen, select "Nexus One" and click on "Copy" to create a copy which you can edit later.

- Once you get a copy, you can rename it to your own configuration name.

- Before you are done, you need to change a few values for both the layouts, landscape and portrait. Follow the screen shot.

Change x dpi, y dpi, Screen Size, Resolution and set it to values as shown above. Do it for both the orientations.

- Save the configuration. Now, whenever you change the configuration to your custom config, since this custom config is for the large screen devices, it would show you how your layouts will look on a real device. It will pick up the xml files correctly whenever you switch your configuration to large screens.

Android OS Versions in the Wild

2010-08-08T12:23:00.000-07:00

The latest stats from Google reveal that most of the Android phones are being upgraded to the latest versions of the OS. Every manufacturer is very keen to get on the bandwagon and capture the market share, which is good for the users and the community.

Image Source : http://developer.android.com/resources/dashboard/platform-versions.html

The above chart gives us an idea of the overall OS spread (August 2, 2010). 59.7% of the Android phones are now running on Android 2.1(Donut). Isn't that great. Nice. And we will definitely see the percentage for Android 2.2(Froyo) increase manifold when manufacturers push updates on the latest version. But, there is a substantial amount of phones still out there running on 1.5, though not a majority. But, if we talk about only numbers, 20.3% of the total Android phones is still a huge number. Now that's a problem.

With Android 1.6 and up, apps can be designed and developed for different density and screen resolutions. The cupcake update doesn't have this feature. There are a few workarounds which enable you to develop in 1.6 and up and still support devices on 1.5, but it's a pain. I am sure many developers will agree with this. Apart from this, there aren't major differences that would hinder developers in making apps to suit all platforms.

And with Android 3.0(Gingerbread), rumors say that it will bring support for tablet sized devices, I am not sure how to absorb this piece of news.

Ongoing notifications in Android

2010-07-17T03:07:00.000-07:00

There is a concept of an Ongoing notifications in Android where you just show a notification for the duration you are performing some background task/process. This special kind of notification cannot be canceled by the used. Also, if you would like to use an animated icon on the status bar, you can do it. As mentioned in the developer docs, you can also use a custom view for your notification.

I have blogged about is here. There's also a link to the source there which you can directly run.

India get's Android 2.1 upgrade for HTC Hero

2010-06-26T22:53:00.000-07:00

What a good morning it is! I thought, I HTC hero would never get a firmware upgrade, and I would be stuck with Android 1.5 forever. But, this morning, I found a dialog asking me to upgrade the firmware. NICE!!!!

But, it seems that this is a two step upgrade process. The first one is the:
"Firmware over-the-air (FOTA) client update & YouTube player Update."

After you install this upgrade, you will finally be able to upgrade to Android 2.1 when the FOTA client is upgraded.

"Android 2.1 Platform Upgrade "

You can find information about this update on HTC india's website. Here is the link.

http://www.htc.com/in/support.aspx

Parcelable - How to do that in Android

2010-06-16T13:52:00.000-07:00

Passing data between activities is quite easy. You would normally do that using the Bundle packed into an intent. But sometimes you need to pass complex objects from one activity to another. One workaround would be to keep a static instance of the object int your Activity and access it from you new Activity. This might help, but it's definitely not a good way to do this. To pass such objects directly through the Bundle, your class would need to implement the Parcelable interface.

For example you have a class called Student, which has three fields.
1. id
2. name
3. grade

You can create a POJO class for this, but you need to add some extra code to make it Parcelable. Have a look at the implementation.

          1: public class Student implements Parcelable{

         2:     private String id;

         3:     private String name;

         4:     private String grade;

         5:  

         6:     // Constructor

         7:     public Student(String id, String name, String grade){

         8:         this.id = id;

         9:         this.name = name;

        10:         this.grade = grade;

        11:     }

        12:     // Getter and setter methods

        13:     .........

        14:     .........

        15:     

        16:     // Parcelling part

        17:     public Student(Parcel in){

        18:         String[] data = new String[3];

        19:  

        20:         in.readStringArray(data);

        21:         this.id = data[0];

        22:         this.name = data[1];

        23:         this.grade = data[2];

        24:     }

        25:  

        26:     @override

        27:     public int describeContents(){

        28:         return 0;

        29:     }

        30:  

        31:     @Override

        32:     public void writeToParcel(Parcel dest, int flags) {

        33:         dest.writeStringArray(new String[] {this.id,

        34:                                             this.name,

        35:                                             this.grade});

        36:     }

        37:     public static final Parcelable.Creator CREATOR = new Parcelable.Creator() {

        38:         public Student createFromParcel(Parcel in) {

        39:             return new Student(in); 

        40:         }

        41:  

        42:         public Student[] newArray(int size) {

        43:             return new Student[size];

        44:         }

        45:     };

        46: }

Once you have created this class, you can easily pass objects of this class through the Intent like this, and recover this object in the target activity.

         1: intent.putExtra("student", new Student("1","Mike","6"));

Here, the student is the key which you would require to unparcel the data from the bundle.

         1: Bundle data = getIntent().getExtras();

         2: Student student = data.getParcelable("student");

This example shows only String types. But, you can parcel any kind of data you want. Try it out.

TextView with HTML content with Images

2010-06-08T06:00:00.000-07:00

Handling HTML content on a TextView is simple as far as the HTML coming in contains a few tags that are by default supported by Android. Simple formatting like bold, italics, font sizes can be handled without even coding a single extra line.

Say, if you have a TextView tv, and there's some HTML string with bold and italicized text, bringing it up on the TextView is pretty simple.

One line code for that:

tv.setText(Html.fromHtml(source));

where the source is actually your HTML string. This works perfectly. But how do we show images if there are any. Well, it's a bit tricky. You have to use the other method that takes in an ImageGetter and a TagHandler.

fromHtml(String source, Html.ImageGetter imageGetter, Html.TagHandler tagHandler)

The tagHandler is for situations where you wish to handle specific tags differently. I didn't wish to do that, so I just passed null there.

Now comes the main task. How do you get the image on to the TextView!!!!

Implement the Html.ImageGetter's getDrawable method which handles downloading the image, or accessing it from the net, and then create a drawable and return that object.

      static ImageGetter imgGetter = new Html.ImageGetter() {
             @Override
             public Drawable getDrawable(String source) {
                   Drawable drawable = null;
                   drawable = Drawable.createFromPath(source); // Or fetch it from the URL
                   // Important
                   drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable
                                 .getIntrinsicHeight());
                   return drawable;
             }
      };

and use the method on the TextView like this.
tv.setText(Html.fromHtml(source, imgGetter, null);

This will load the TextView with the image. But this call to the getDrawable method is not asynchronous. So, until and unless that method returns, you UI will be blocked. In my case, I am creating the drawable from a local image, so, it didn't take much time. But, if you want to fetch an image from the web, you have to make this call in a separate thread, so that the UI is not blocked.

So, check your HTML string if they contain any images that have to be downloaded. If you find any, create a thread that download that image, saves it somewhere and returns you the location of that file. Now, change the src tags to point to the local images, and call setText method on the TextView.

And that should do it. The important thing to remember is, you have to change the HTML to point it to the file that you have downloaded.

Sample Source code : http://code.google.com/p/myandroidwidgets/source/browse/#svn/trunk/TextViewHTML

This sample doesn't use threads. So, your UI will be blocked unitl the image here is downloaded. So, keep waiting. :)

Checking Network Availability

2010-06-01T12:14:00.000-07:00

I have seen a few applications which first try to initiate a network connection before checking if any network is available or not. And then, if the request fails, they toast a message saying "No network available". This might not be the right approach in most of the situations. Before initiating a connection, we should always check the availability of a network and then proceed. Android provides a simple way by which you can know the status of the active network if any. So, why not use it. It's very simple.

The code:

public static boolean isNetworkAvailable(Context context) {
            boolean value = false;
            ConnectivityManager manager = (ConnectivityManager) context
                             .getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo info = manager.getActiveNetworkInfo();
            if (info != null && info.isAvailable()) {
                           value = true;
            }
            return value;
}

Simple Drag n Drop on Android

2010-04-07T12:20:00.001-07:00

Till now, there is no Drag and Drop like control on the Android. This feature might come in handy in a few situations to improve the usability of your apps. Here is a simple Drag and Drop app which allows you to drag a button and drop it anywhere on the screen.
Theory: Go for a FrameLayout.
FrameLayout is designed to block out an area on the screen to display a single item. You can add multiple children to a FrameLayout, but all children are pegged to the top left of the screen. Children are drawn in a stack, with the most recently added child on top.
In our main layout, we have a single button. We write a touch listener which will track the touch events and also help us to move the button around the screen. In this example, we will not be moving the button, but it’s image which we set to a ImageView. Also, instead of actually moving the ImageView, we will change the padding of the ImageView as the mouse moves, which will give an impression of the ImageView being moved.

The source code for this can be found on this link.
Drag and Drop example

Custom ProgressBar for Android

2010-04-05T02:33:00.000-07:00

We will try to make a new progress bar with our own progress animation. It's pretty simple and can be easily set up to run in few minutes. Here we go.

1. MyProgressBar.java
This class extends the ProgressBar class and has two methods that we would need to call to start and stop the animation.

To start the animation: call startAnimation()
To stop the animation: call dismiss()

Basically, we run a thread which keeps on switching the images. That's it.

2. myprogressbar.xml

This is the layout that the MyProgressBar would be using. This animation would be using 9 images which are in the drawable folder.

You can check out the whole project from the SVN. Here is the link.

https://myandroidwidgets.googlecode.com/svn/trunk/Custom_Progress_Bar

Custom AutoComplete for Android

2010-04-03T12:59:00.001-07:00

The default custom AutoCompleteTextView is quite a nice widget. But if you want to extend it's functionality, you will need to write your own custom widget. As an example, if you wish to have a EditText for a "To" address field as any email application has, where you want to collect multiple selections from the list that pops up, you will need to extend the AutoCompleteTextView class and write your own small little widget. It's very simple to create one that will suit your need.
So here we go.
1. Class CustomAutoComplete.java

package com.beanie.example.widgets;
import android.content.Context;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.widget.AutoCompleteTextView;
  
public class CustomAutoComplete extends AutoCompleteTextView {
    private String previous = "";
    private String seperator = ";";
    public CustomAutoComplete(final Context context, final AttributeSet attrs, final int defStyle) {
        super(context, attrs, defStyle);
        this.setThreshold(0);
    }
    public CustomAutoComplete(final Context context, final AttributeSet attrs) {
        super(context, attrs);
        this.setThreshold(0);
    }
    public CustomAutoComplete(final Context context) {
        super(context);
        this.setThreshold(0);
    }
    /**
     * This method filters out the existing text till the separator
     * and launched the filtering process again
     */
    @Override
    protected void performFiltering(final CharSequence text, final int keyCode) {
        String filterText = text.toString().trim();
        previous = filterText.substring(0,filterText.lastIndexOf(getSeperator())+1);
        filterText = filterText.substring(filterText.lastIndexOf(getSeperator()) + 1);
        if(!TextUtils.isEmpty(filterText)){
            super.performFiltering(filterText, keyCode);
        }
    }
    /**
     * After a selection, capture the new value and append to the existing
     * text
     */
    @Override
    protected void replaceText(final CharSequence text) {
        super.replaceText(previous+text+getSeperator());
    }
    public String getSeperator() {
        return seperator;
    }
    public void setSeperator(final String seperator) {
        this.seperator = seperator;
    }
}

This class is the main widget class that extends thet AutoCompleteTextView. You have to override 2 methods,

protected void replaceText(final CharSequence text)

protected void performFiltering(final CharSequence text, final int keyCode)

2. You main layout file (main.xml)

&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent"&gt;
    &lt;com.beanie.example.widgets.CustomAutoComplete android:layout_width="fill_parent"
        android:layout_height="wrap_content" android:id="@+id/autocomplete"/&gt;
&lt;/LinearLayout&gt;

3. Now we test it. This is your activity class.

package com.beanie.example;
import android.app.Activity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import com.beanie.example.widgets.CustomAutoComplete;
  
public class TestAutoComplete extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        CustomAutoComplete myAutoComplete = (CustomAutoComplete)findViewById(R.id.autocomplete);
        ArrayAdapter&lt;String&gt; adapter = new ArrayAdapter&lt;String&gt;(this, android.R.layout.simple_dropdown_item_1line);
  
        adapter.add("aaaa");
        adapter.add("abaa");
        adapter.add("acaa");
        adapter.add("adaa");
        adapter.add("aaba");
        adapter.add("aaca");
        adapter.add("aaba");
        adapter.add("aaae");
        
        myAutoComplete.setAdapter(adapter);
    }
}

Voila, you are done. Here’s a screenshot of our Custom Auto-Complete Text view at work.

You can also change the separator from the default “;” to any other character like a “,” or anything else.
On the adapter, you call the method setSeparator(String any);
Now you have your own custom auto-complete widget for Android.

For this particular example, however, Android provides you a widget by default. MultiAutoCompleteTextView is specifically designed to handle such kind of input.

Custom Buttons on Android

2010-03-24T11:22:00.000-07:00

The default buttons are a kind of ugly when you change the background of an activity. In some scenarios, you will be forced to change the way your Buttons look. To achieve this, you need not create your own custom Button class. The Android framework provides ways to achieve this with minimum effort.

Let's say we have a Button in a simple layout for which we need to do this. Here is a simple layout with just a button.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<Button
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/click"
    android:background="@drawable/custom_button"
    />
</LinearLayout>

Note the android:background attribute on the Button. This refers to a drawable which is an xml in your drawable folder which will determine the different states of your button, namely,
1. default
2. pressed
3. focussed

This is the code for custom_button.xml:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_focused="true" android:state_pressed="false" android:drawable="@drawable/focussed" />
    <item android:state_focused="true" android:state_pressed="true" android:drawable="@drawable/focussedandpressed" />
    <item android:state_focused="false" android:state_pressed="true" android:drawable="@drawable/pressed" />
    <item android:drawable="@drawable/default" />
</selector>

For this selector tag, note all the drawable attributes. You will have different png images for each of the states which you would put in your drawable folder.

Now you have your own custom button with customized look and feel.

Youtube/Market Intent for Search in Android

2010-03-11T04:07:00.000-08:00

Here is a trick that would help other applications that need to open search results for videos based on a particular keyword.

You need to create an implicit Intent and trigger it. Here is a snippet of code that works.

For Youtube
Intent intent = new Intent(Intent.ACTION_SEARCH);
intent.setPackage("com.google.android.youtube");
intent.putExtra("query", "Android");
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);

Here, "Android" is the keyword. Now, the Youtube app will show you videos with the keyword "Android"

For Market
Similarly, by changing only the package name, you can bring up search results with the Android Market app as well.

Intent intent = new Intent(Intent.ACTION_SEARCH);
intent.setPackage("com.android.vending");
intent.putExtra("query", "Android");
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);

For Contacts
The package name for the Contacts app is "com.google.contacts".

You just need the package name of the target app if you don't want the Resolver activity to show up. This might work for other google apps as well. I haven't checked though.

Sign your Android applications for release

2010-02-25T23:00:00.000-08:00

The process of application signing can be very confusing for new developers. But, once you have done it 2-3 times, it will be more like a chore for you after that. It's not very complicated at all. So, here are the steps that you need to follow.

Note: If you already have a self-signed certificate/keystore, skip to step 2(b):

Step 1: Right click on the Android project. From the context menu, select, Android Tools -> Export Signed application package. In the dialog that will open, you will see the name of your project. If you have selected the wrong project, here is a chance to correct yourself. Click on "Next".

Step 2: The next screen is the most complicated screen that you will get in this process. Here, you can have two situations.

a. If you don't have a keystore already, you will need to create one first. Once created, you should preserve this keystore somewhere, safely, so that you don't accidentally delete it. You will need this keystore everytime you want to sign and update your application to the Android Market. Please, please, please, DO NOT LOSE THIS KEYSTORE.

Since, we are creating a new keystore this time, select the second radio, and browse to a location where you want you new keystore to be saved. Enter and confirm a password. Remember this password. Click on "Next".

Enter all the fields in this screen and press enter. Now your keystore will be created. Please rememeber all your passwords. Else, this keystore will be useless for you later.For simplicity, keep both the passwords same.

On this screen, specify a name and location of the apk and click on "Finish". Your signed application package will be created for you in the location you have mentioned here. You can now take this apk and directly upload it to the Android market, or put it on your phone.

b. When you already have a kestore, it's more easier to sign your application. On the second screen, select, "Use existing keystore". Enter the location of the keystore and password. Click on "Next". On the next screen, select you alias from the drop down, enter the alias password, click on "Next". On the next screen, specify a name and location where you want the apk to be created and click "Finish". You are done now.

Isn't it simple? Just one point to note: If you are using an old ADT version, this option of signing your apps from eclipse might now be there. In such a case, you will have to do it through command line. You can find many tutorials on how to achieve that.

The official document can be found here: http://developer.android.com/guide/publishing/app-signing.html#signing

Thanks,

Kumar

Market your apps aggresively

2010-02-02T02:46:00.000-08:00

You have created a cool app, and have also updated it unto the Android Market. Great!!!! So, do you sit idle and wait for people to buy your app? Is your work done? A big "NO".

The Android Market has around 20000 apps today. And new apps are pouring in daily in large numbers. How do you tell people/users, "Hey, people, here is a cool app that you should check out"? From among these 20000 apps, people will never bother to enter your app's name in the search box. They just don't have the time.

So, how do you go about and spread the word about your app? Well, here are some tips.

1. Create a website for your app and update it regularly.
2. Create a blog for your app and provide as much information as you want about upcoming features, bugs and maybe tutorials.
3. Use twitter to reach to your friends.
4. Facebook also is quite a good medium through which you can broadcast your message on everybody's walls.
5. Create a forum for your app where people can come in and enter their issues/experiences.
6. Request some Android app websites to publish a review for your app.
7. Submit links to your website/blog to a few bookmarking websites, don't over-do it though.
8. If you want, you can also submit to alternate websites for the Android Market for people who don't have access to the market.
9. Make sure that your app has an apt description about what it does when you upload it to the market.
10. Ask for feedback from people who use your application regularly.

Market on Emulator

2009-11-06T09:22:00.001-08:00

So, finally, we have Android Market on our emulators. Now, since it is possible, a developer can create any number of emulators with the android market on it, and login to different google accounts, and try to increase his app's ratings. This is actually too dangerous. Google doesn't discriminate requests from market apps on such emulators, and still accepts ratings and reviews. I don't know how Google can now stop this, since, everybody and anybody can now have access to the market place from his emulator. But, I am happy, :) Till Google takes any steps to curb this backdoor entry through the emulators, we can obviously expect some of those comments/reviews on the apps to be just spam. :( Google market has got to do something to stop this, and probably they will.

Android Market on Emulator

2009-11-04T12:03:00.000-08:00

Wow, This is cool. Finally, I am able to run the Android Market on the emulator. And also, see all the paid apps and copy-protected app, right here on my emulator.

What do you need?

Well, the basic SDK. 1.5, 1.6 or 1.1

And then, go to the HTC website where you can find the images/recovery images. Download the version (system image only) which you want to run.

http://developer.htc.com/google-io-device.html#s3
(Download the System Image zip)

Extract the files of this zip. There's a system.img file which you will need in the next steps.

Create an AVD (1.1, 1.5 or 1.6) depending on your requirements.

Copy this system.img file into the avd directory. For example, if you created an avd named "MyPhone", go to .avd\MyPhone\ and paste this system.img file here.

Now start the emulator. Voila, You are ready to go. After you sign in with a google account, your phone is ready to use. You now have access to all the market apps right from your emulator.

Note: If you are not able to run it successfully, and if you are getting Network communication error, please download the AVD that I have created from this link.

Link for 1.5 image
www.4shared.com/file/147420185/da5381e1/avd.html

Link for 1.6 image
http://www.4shared.com/file/165624746/fc72c3ed/system.html

Blogaway 1.0 for Android Phones

2009-10-29T12:20:00.000-07:00

A simple blogger client to read, post and manage your blogspot account feeds. A convenient way to keep you connected. This initial version is still under active development. More and more features will get added so that you can have a real Blogging experience. Features for 1.0 - Multiple blog account support - Multiple feeds under one account - Create, publish or save as drafts - Blogroll to read public Blogspot feeds - Captcha unlock account - Set default account to create new post, comments etc. Future improvements - View Comments - Post Comments - Add pictures/videos to posts - Manage your accounts - Delete feeds and accounts - Support for other blog feeds other than Blogspot I will be updating this application at regular intervals with more features. Currently, adding tags to your posts is not supported. I suppose this feature is one of the most important feature for such a client.

Android 2.0 !! Overview

2009-10-27T23:13:00.001-07:00

Here is a list of apps that have been removed from the emulator. 1. Calendar 2. Camcorder 3. Google Maps The icons now have a new look and feel. Though I like the Donut icons, I guess, icons will keep changing. One issue with the default-email client that is supposed to support Exchange. I have successfully added an exchange account. But I am not able to see any new mails, and also, the mails I sent are still in the Outbox. When I go to contacts to add contacts from my Exchange Account, the application crashed. I couldn't test if the Contact's application can really synchronize with the exchange server. As for Google Maps, I think it will be shipped with the handsets only, as a separate application, and your code that uses Google Maps features will work on handsets, but as of now, there is no way to test such applications, unless you get it installed on your emulator. A lot of animated transitions when you switch between screens. And the new "Unlock" feature to unlock the key pad looks cool, but I guess, it would be a bit uncomfortable to use. You should need minimum effort to unlock your keypad. On the surface, you will basically find a complete UI change. I haven't yet digged into the new APIs. Have an Eclair !!!!! :)

Android 2.0 !!! Where is Google Maps

2009-10-27T14:01:00.001-07:00

Just saw Android 2.0 (Eclairs) and downloaded it. Started the emulator, and compiled my project with 2.0 settings. I was surprised to see red marks all over the place. After looking at the console, I figured out that Android 2.0 doesn't have in-built Maps API. If your application uses the Google Maps API, then you are in for a surprise. Read on. Now what? In the emulator too, I didn't find the Google Maps application. Damn. But, just to test if my other functionalities were intact with the new Android 2.0, I added the maps.jar avaialble in the Android SDK as an external jar. I thought this would solve the problem. All compile errors vanished. But when I tried to install my app, the console said, "Installation error: INSTALL_FAILED_MISSING_SHARED_LIBRARY" To avoid this installation error, you have to remove this line from the manifest file so that Android detects the maps.jar as an external API and not an internal one. uses-library android:name="com.google.android.maps" Now, your app will be installed without any errors. But, since there is no Google Maps application, you cannot launch or test any Google Maps feature that you application depends on. Needless to say, it will of course be available on our handsets, but this is very disappointing.

Orientation independent applications

2009-10-21T10:29:00.001-07:00

The Android phones detect orientation changes when you tilt your phone from landscape to portrait or vice-versa. It’s a cute feature. Well, most of the time you would be using your phone in the portrait mode. But for the phones that have a full QWERTY keyboard, the orientation automatically changes to landscape mode when you slide out your keyboard. If your application is not designed to handle such orientation changes, the usability of your application might decrease to an extent at which it might get completely unusable, or at the least, very inconvenient for the user.

How to handle it? It is actually very simple. You would have put all your layout xml files in a folder called “res/layout”. This is the default location from where the layout files are picked up, i.e , when your phone is in portrait mode. You just need to create one more folder “res/layout-land” where you put you xml files, with the same name, but with a different layout, which would be convenient for the user to view when in portrait mode. This is all you have to do.

Next time, when the orientation is changed, your layout files will be picked up from the layout-land folder, and will be applied to your UI.

Enjoy….

Gesture Detection on Android

2009-10-05T09:55:00.000-07:00

I just got my gesture detection code working. It's a fun way and a convenient way as well to enhance the usability of your application. So, here is the code that gets you going. First, for the Activity that you want to detect gestures, the OnGestureListener interface has to be implemented. Then, you need to override the methods and implement them. And finally, you need to implement the onTouchEvent method of the activity that will trigger the gesture listener code.

        1: package com.beanie.androidco;

       2:  

       3: import android.app.Activity;

       4: import android.os.Bundle;

       5: import android.view.GestureDetector;

       6: import android.view.MotionEvent;

       7: import android.view.GestureDetector.OnGestureListener;

       8:  

       9: public class GestureDemo extends Activity implements OnGestureListener {

    private GestureDetector gestureDetector;

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        gestureDetector = new GestureDetector(this);

    }

  

    @Override

    public boolean onTouchEvent(MotionEvent event) {

        return gestureDetector.onTouchEvent(event);

    }

  

    @Override

    public boolean onDown(MotionEvent e) {

        // Do something

        return false;

    }

  

    @Override

    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,

            float velocityY) {

        // Do something

        return false;

    }

  

    @Override

    public void onLongPress(MotionEvent e) { 

        // Do something

    }

  

    @Override

    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,

            float distanceY) {

        // Do something

        return false;

    }

  

    @Override

    public void onShowPress(MotionEvent e) { 

        // Do something

    }

  

    @Override

    public boolean onSingleTapUp(MotionEvent e) { 

        // Do something 

        return false;

    }

}

The most commonly used method would probably be the onFling method, where you have to check for a threshold velocity and displacement before you would want to trigger an action. For detecting Left Fling, Right Fling, Scroll down/up, you will need to write some extra code in the corresponding methods. Enjoy...

SMS Blocking in Android

2009-09-07T11:07:00.000-07:00

Recently, I tried to develop an app that would block sms from certain numbers that you can choose. It seems that you cannot completely block the incoming sms. These were the problems that I faced while working with this app.

1. There are no APIs supplied, that handles the SMS inbox (I mean, no content providersm which can be directly queried to fetch records from the sms table). However, you have a workaround of finding the tables where the sms is stored, and then querying and updating that table. Well, there is actually a content provider, that exposes this table to other applications, but it is not documented anywhere. So, I have to hardcode the column values. This is potentially dangerous, if in the next Donut release, Google changes the column names, my application would fall apart.

2. On receiving of an SMS, I have 2 things to do. Remove the SMS from the sms table, and disable the notification. Deleting the sms from the table was pretty easy, but I couldn't find a way to remove the Notification. Perhaps, there is no way that we can disable this notification. One workaround might be, to temporarily change the Notification settings, the moment you sense an incoming message from a blocked number. And, after you delete the message from the sms table, you just turn on the notification. I haven't worked on this, but this might just work.

3. If the Messaging application is already open, and an sms arrives, weird things start to happen. I can see the blocked sms being deleted, and the list of sms gets updated. But the next message in the list is marked as "Unread". Probably, this is done by the Notification, I don't know.

4. SMS broadcast, is definitely, an un-ordered one. So, the easiest way, that could have worked, would have been just to abort the broadcast. But in this case, you don't have this option. so, once you recieve this broadcast, you have to manually go and delete the message, by matching the incoming number, timestamp etc. Timestamp method isn't foolproof. Because, the timestamp you receive, is the timestamp of the broadcast, and not the time when the sms is written into the DB. So they wont match. You should pick up the incoming number, and check for the timestamp within a range of about 1 seconds. This should give you the sms that you need to delete.

5. There's another problem. When you recieve the broadcast, the system wont write the sms into the table, before it is sure that all the broadcast receivers have done their work. So, it waits for some time, and then writes the sms into the table. Before this, if you try to delete the sms, obviously, you would not find it in the table. So, make your code sleep for about a second, and then go and delete the SMS. That should do it. But, the most important problem still persists. THE NOTIFICATION. I guess, it can't be removed.

Android : Sliding Drawer Example

2009-08-22T07:55:00.001-07:00

If you have lot’s of stuff to put on your screen for a single activity, you should probably go for the SlidingDrawer widget. It is very simple to use, and looks cute. Here are the steps that you need to do for bringing up the sliding drawer on your activity.

Here is a sample application displaying how to code up a sliding drawer. It's pretty simple, and I don't think it needs more explanation.

<SlidingDrawer android:id="@+id/slidingDrawer1"
        android:layout_width="fill_parent" android:layout_height="fill_parent"
        android:topOffset="50dip" android:handle="@+id/handle"
        android:content="@+id/content">

The sample project sets up a Sliding Drawer at the bottom of the screen. You can change it to appear at place of the screen. You just need to change/adjust some properties of the SlidingDrawer.

The orientation property can be set to either "horizontal" and "vertical"
There are properties like "topOffset", "bottonOffset", "rightOffset" and "leftOffset" with which you can position your drawer anywhere.
With a few more changes, you can attach backgrounds/images to the whole SlidingDrawer. For example, I have added a color background to the content of the Sliding Drawer.

Update: Here is the link to the source code which shows how to cook up a simple sliding drawer.

FileWriter in Android

2009-08-13T09:35:00.001-07:00

This is a pretty handy API that you can use to write a string of information to a file on the device. It doesn’t need a StreamWriter or BufferedWriter or FileOutputStream. It is short and sweet.
            FileWriter fWriter;
            try{
                 fWriter = new FileWriter(“\sdcard\filename.txt”);
                 fWriter.write(yourString);
                 fWriter.flush();
                 fWriter.close();
             }catch(Exception e){
                      e.printStackTrace();
             }
The flush() and close() calls are important here, and also make sure that the “sdcard” is mounted. Else, you can use a path such as “data\data\com\yourpackage\filename.txt” which would create a file in the data directory of your package.

Scrollview in Android

2009-08-13T09:29:00.001-07:00

I never noticed, or realised how an application’s UI would render when the orientation changed, since most of the time I tested my apps on the emulator. But one fine day, when a friend of mine walked in and asked to change the orientation, I shocked to see that the layouts didn’t fit in the landscape view.
Well, the solution!!!
Wrap your layouts in a parent ScrollView, so that, when the orientation changes, you will be able to at-least scroll and view the whole layout. How the UI looks, is however a different concern.

Relative Layouts vs Linear Layouts

2009-08-13T09:24:00.001-07:00

From the very first day, I hated Relative Layouts. I struggled with layouts in general during my initial days till I figured out that Linear Layouts can create any kind of complex layout you need. By using only the Linear Layouts, you can create whatever you want. I had always wondered what was the purpose of the other available layouts.
I was a fan of the Linear Layouts till the day I hit the dead end. With SDK 1.5, pressing for the limit up to which your view hierarchy can be deep, problems started with my existing apps. I was able to remove the errors by removing a layout or two. And then, there was a case, where, I couldn’t remove a level. I was hitting the StackOverflow exception all the time. Frustrated, I posted my query to Google Groups, and guess what, Romain Guy responded, asking me to remove or simplify my view hierarchy. Well, if I were to listen to him, it would mean converting some Linear Layouts to Relative Layouts. And since I didn’t understand Relative Layouts then, I though it was a big big ask. But I tried, and guess what, now my UI is faster, simpler and I don’t get that StackOverflow exception.
I have now realized that though it is easy to use LinearLayouts, but RelativeLayouts not only make your UI load faster, but also is easier to render (at least for me). I have changed all my Linear Layouts to Relative ones, wherever possible.
I also watched the Google I/O videos that gave me a lot of information regarding how to code for Android platform. One of them I would like to mention in my next blog would be about the ListView, the most widely used widget, and i guess, the most wrongly used as well.
Keep droiding….

A Custom ListView for Android

2009-07-12T00:51:00.001-07:00

I have been thinking about starting a new blog for Android stuff for quite a long time. And today, I found some time for the same. So here goes my first post. This is about developing your own custom list view. The List View is a very powerful UI element for the android platform. And it provides a lot of customizing features as well. Let’s jump into the details right away.
For this example, I will be using an example for a phone book entry, with the contacts having basic information like “name”, “phone” and “email”.

Step 1: Lets create a POJO class for the phone book.
Class name : Phonebook.java
Not a complex code. Just the three fields, a constructor and the getters and setters. That’s it.
Step 2: Lets create the layout that each row of the List View is going to look like. I prefer to do this layout in xml rather than through coding/programmatically. xml stuff is pretty easy to develop.
File name : phone_row.xml

This layout has three Text Views, tvContact, tvMobile and tvMail which we will be using in our code. We don’t need to touch any other elements from this file, if you should have to edit this xml, do it carefully.

Step 3: Now, lets create a class which our custom adapter will be calling to render each row of the List View. Here, we need the layout file created in Step 2. This class should extend any layout type, e.g, LinearLayout, TableLayout, etc. In my example, I am using a LinearLayout.

Class name : PhonebookAdapterView.java
In this class, create a constructor with two parameters, Context and the Pojo class Phonebook. And, inside the constructor, set the fields to the text views. The “this.setTag(entry)” will enable us to get info on the phonebook entry, when we use the listener for List View.

Update: I have deleted this class from the example, and have used the efficient way recommended for ListView. Checkout out the code.

Step 4: Now, create the Phonebook adapter class which extends the BaseAdapter. This will be used to set a list of Phonebook items to the list view with our customized layout.

Class name : PhonebookAdapter.java
This class has a bit of coding, and changes to be made in the default methods that comes in when you extend the BaseAdapter class, however it is simple enough. A new constructor and two new private members is all that you have to include.
Override the methods as given in the code. The method getView is the important one. Here, we call our PhonebookAdapterView class.

Now, you are done. Your custom list view has been created. The final step would be testing the custom list view. Just create and activity with a listview. Then create an instance of the PhonebookAdapter class passing the parameters (Context and list of Phonebook objects)

Then, set this adapter to the list view. You are done. Here is the output.
Here is the link where you can find all the source code as an Android Project (1.5 compatible).

Full source code is here.

Update: I have updated the example, to include a button on each line item, which when clicked, removes that item from the List View.