Base class for code that will receive intents sent by broadcastIntent(). You can either dynamically register an instance of this class with Context.registerReceiver() or statically publish an implementation through the <receiver> tag in your AndroidManifest.xml. Note:    If registering a receiver in your Activity.onResume() implementation, you should unregister it in Activity.onPause(). (You won't receive intents when paused, and this will cut down on unnecessary system overhead). Do not unregister in Activity.onFreeze(), because this won't be called if the user moves back in the history stack.

Note that, although the Intent class is used for sending and receiving these broadcasts, the Intent broadcast mechanism here is completely separate from Intents that are used to start Activities with Context.startActivity(). There is no way for an IntentReceiver to see or capture Intents used with startActivity(); likewise, when you broadcast an Intent, you will never find or start an Activity. These two operations are semantically very different: starting an Activity with an Intent is a foreground operation that modifies what the user is currently interacting with; broadcasting an Intent is a background operation that the user is not normally aware of.

The IntentReceiver class (when launched as a component through a manifest's <receiver> tag) is an important part of an application's overall lifecycle.

Topics covered here:

1. Receiver Lifecycle
2. Permissions
3. Process Lifecycle

Receiver Lifecycle

An IntentReceiver object is only valid for the duration of the call to onReceiveIntent(Context, Intent). Once your code returns from this function, the system considers the object to be finished and no longer active.

This has important repercussions to what you can do in an onReceiveIntent(Context, Intent) implementation: anything that requires asynchronous operation is not available, because you will need to return from the function to handle the asynchronous operation, but at that point the IntentReceiver is no longer active and thus the system is free to kill its process before the asynchronous operation completes.

In particular, you may not show a dialog or bind to a service from within an IntentReceiver. For the former, you should instead use the NotificationManager API. For the latter, you can use Context.startService() to send a command to the service.

Permissions

Access permissions can be enforced by either the sender or receiver of an Intent.

To enforce a permission when sending, you supply a non-null permission argument to broadcastIntent(Intent, String) or broadcastIntent(Intent, String, IntentReceiver, android.os.Handler, int, String, Bundle). Only receivers who have been granted this permission (by requesting it with the <uses-permission> tag in their AndroidManifest.xml) will be able to receive the broadcast.

To enforce a permission when receiving, you supply a non-null permission when registering your receiver -- either when calling registerReceiver(IntentReceiver, IntentFilter, String, android.os.Handler) or in the static <receiver> tag in your AndroidManifest.xml. Only broadcasters who have been granted this permission (by requesting it with the <uses-permission> tag in their AndroidManifest.xml) will be able to send an Intent to the receiver.

See the Security Model document for more information on permissions and security in general.

Process Lifecycle

A process that is currently executing an IntentReceiver (that is, currently running the code in its onReceiveIntent(Context, Intent) method) is considered to be a foreground process and will be kept running by the system except under cases of extreme memory pressure.

Once you return from onReceiveIntent(), the IntentReceiver is no longer active, and its hosting process is only as important as any other application components that are running in it. This is especially important because if that process was only hosting the IntentReceiver (a common case for applications that the user has never or not recently interacted with), then upon returning from onReceiveIntent() the system will consider its process to be empty and aggressively kill it so that resources are available for other more important processes.

This means that for longer-running operations you will often use a Service in conjunction with an IntentReceiver to keep the containing process active for the entire time of your operation.

Known Direct Subclasses

Public Constructors

Public Methods

Methods inherited from class java.lang.Object