I have broadcastReceiver defined in AndroidManifest.xml. Do I need to unregisterReceiver in activity's onDestroy and onPause? If yes, how to do it? Note that I didn't registerReceiver by code. Just defined in the AndroidManifest.xml. If required , then how to register again onStart and onResume?
<receiver android:name="com.me.broadcastReceiver.test" >
<intent-filter>
<action android:name="abc" />
</intent-filter>
</receiver>
Nope, you do not need to unregister your receiver if it is declared in the manifest.
You can still disable it if you want (for example check this answer).