如何在Android中定义自定义事件和事件监听器？

Question

I'm a starter in Android app development, and my experience in Java development is also minimal.

I'm working on a very basic context-aware application and I want to understand how can I notify my activity class of some custom event? (unlike onClick()). So if I have a class which is responsible for monitoring some resource. (For simplicity, let's assume a Timer class which monitors time and notifies the Activity class every hour).

How can my activity class 'subscribe' and listen for such events from the Timer class?

I would really appreciate if you provide some code example and perhaps how event handling works in Android/Java. Thanks for your time and help!

Answer 1

Use Broadcast Intents to notify listeners of system or application/custom events..

send a Broadcast using sendBroadcast method whenever your custom event occurs..

Intent intent = new Intent(NEW_Intent);
intent.putExtra(“Test”,Test1);
sendBroadcast(intent);

To create a new Broadcast Receiver(which will listen to your event/broadcast), extend the BroadcastReceiver class and override the onReceive event handler.The onReceive method will be executed when a Broadcast Intent is received that matches the Intent Filter used to register the receiver.

Register your receiver in either Manifest file or in the code..

//in xml

<receiver android:name=”.ReceiverName”>
<intent-filter>
<action android:name=”com.paad.action.NEW_INTENT”/>
</intent-filter>
</receiver>

//in code..

IntentFilter filter = new IntentFilter(NEW_INTENT);
ReceiverName r = new ReceiverName();
registerReceiver(r, filter);

Answer 2

您可以使用Intent类： http ： //developer.android.com/reference/android/content/Intent.html