Ongoing notifications in Android

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

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

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

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

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;
 }