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Android - Basic Steps (Notifications)

User Notifications

Types:

  • Toast
  • Notification Area Notifications

Tip

To use the notification vibration, establish the permission in the AndroidManifest.xml file

   <uses-permission android:name="android.permission.VIBRATE" >
    </uses-permission>


Broadcast

  • Base class for components that receive and react to events
  • When event occur is represented as Intent, then are broadcast to system
    • The Intent routes to BroadcastReceiver
    • The BroadcastReceiver receive on the method onReceive()

Broadcast

  • Events can be broadcast in Order or Normal way
    • Normal - Undefined order and if there are two or more BroadcastReceivers can process the event at the same time.
    • Order - Deliver the intent one at the time in priority order
  • Can also be Sticky or Not Sticky
    • Sticky  
      • Store intent after initial broadcast
      • Is useful to record system changes like the battery status
      • Is disposed after the event finish 
    • Non Sticky
      • Discard intent after initial broadcast
      • Is useful to record that an event has occurred
    • The broadcaster must have the permission BROADCAST_STICKY

Broadcast Order

To send the Intent in an order can use the method sendOrderedBroadcast()
  • With two parameters send in priority order (Intent intent, String receivingpermission)
  • With more parameters have better control

BroadcastReceiver

  • The broadcastReceiver can register in
    • AndroidManifest (Statically)
      • Atributes  - android:exported - if can receive from other applications
      • It is registered when system boot or when package are added at runtime.
      • The mehods to register at runtime are:
        • Context.registerReceiver()
        • LocalBroadcastManager.registerReceiver()
    • Using the method registerRecewiver()  (Dinamically)
        <receiver
            android:name=".Receiver"
            android:exported="false" >
            <intent-filter>
                <action android:name="course.examples.BroadcastReceiver.show_toast" >
                </action>
            </intent-filter>
        </receiver>

  • BroadcastReceiver 
    • Receive on the method onReceive() with the context and intent as parameter
    • broadcast an intent is a relative expensive 
    • broadcast runs in the main thread 
    • Receiver is not consider valid once onReceive() returns
    • Broadcast receivers can't start asynchronous operations 
  • When the method sendOrderedBroadcast is invoke, it can collect information from others broadcastReceiver with the method getResultData()
new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context,
"Final Result is " + getResultData(),
Toast.LENGTH_LONG).show();
}
}, null, 0, null, null);
  • In each broadcastReceiver can put data with the method 
setResultData(info_to_be_collected);

Debug

  • Get more information in the Log using in the Intent to be broadcast
    • Intent.setFlag(FLAG_DEBUG_LOG_RESOLUTION)
  • Use ADB tool 
    • To see which receivers are registed
  • Use dumpsys command
    • %adb shell dumpsys activity b
      • show broadcast receivers that are dynamically registered
    • %adb shell dumpsys package
      • show broadcast receivers that are statically registered




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