reading-notes

Intent Filters

• Intent filter is a property that used in your app to allow other apps use a feature of your app and It is added in the manifest file if you want to use it

Allowing Other Apps to Start Your Activity

• To allow other apps to start your activity in this way, you need to add an <intent-filter> element in your manifest file for the corresponding <activity> element.

• When your app is installed on a device, the system identifies your intent filters and adds the information to an internal catalog of intents supported by all installed apps. When an app calls startActivity() or startActivityForResult(), with an implicit intent, the system finds which activity (or activities) can respond to the intent.

• The system may send a given Intent to an activity if that activity has an intent filter fulfills the following criteria of the Intent object:

1. Action : Usually one of the platform-defined values such as ACTION_SEND or ACTION_VIEW.
2. Data : A description of the data associated with the intent.
3. Category : usually related to the user gesture or location from which it’s started ,all implicit intents are defined with CATEGORY_DEFAULT by default.

Handle the Intent in Your Activity

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.main);

    // Get the intent that started this activity
    Intent intent = getIntent();
    Uri data = intent.getData();

    // Figure out what to do based on the intent type
    if (intent.getType().indexOf("image/") != -1) {
        // Handle intents with image data ...
    } else if (intent.getType().equals("text/plain")) {
        // Handle intents with text ...
    }
}

Return a Result

// Create intent to deliver some kind of result data
Intent result = new Intent("com.example.RESULT_ACTION", Uri.parse("content://result_uri"));
setResult(Activity.RESULT_OK, result);
finish();