Android equivalent to NSNotificationCenter
The best equivalent I found is LocalBroadcastManager which is part of the Android Support Package.
From the LocalBroadcastManager documentation:
Helper to register for and send broadcasts of Intents to local objects within your process. This is has a number of advantages over sending global broadcasts with sendBroadcast(Intent):
- You know that the data you are broadcasting won't leave your app, so don't need to worry about leaking private data.
- It is not possible for other applications to send these broadcasts to your app, so you don't need to worry about having security holes they can exploit.
- It is more efficient than sending a global broadcast through the system.
When using this, you can say that an Intent is an equivalent to an NSNotification. Here is an example:
ReceiverActivity.java
An activity that watches for notifications for the event named "custom-event-name".
@Overridepublic void onCreate(Bundle savedInstanceState) { ... // Register to receive messages. // This is just like [[NSNotificationCenter defaultCenter] addObserver:...] // We are registering an observer (mMessageReceiver) to receive Intents // with actions named "custom-event-name". LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver, new IntentFilter("custom-event-name"));}// Our handler for received Intents. This will be called whenever an Intent// with an action named "custom-event-name" is broadcasted.private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { // Get extra data included in the Intent String message = intent.getStringExtra("message"); Log.d("receiver", "Got message: " + message); }};@Overrideprotected void onDestroy() { // Unregister since the activity is about to be closed. // This is somewhat like [[NSNotificationCenter defaultCenter] removeObserver:name:object:] LocalBroadcastManager.getInstance(this).unregisterReceiver(mMessageReceiver); super.onDestroy();}SenderActivity.java
The second activity that sends/broadcasts notifications.
@Overridepublic void onCreate(Bundle savedInstanceState) { ... // Every time a button is clicked, we want to broadcast a notification. findViewById(R.id.button_send).setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { sendMessage(); } });}// Send an Intent with an action named "custom-event-name". The Intent sent should // be received by the ReceiverActivity.private void sendMessage() { Log.d("sender", "Broadcasting message"); Intent intent = new Intent("custom-event-name"); // You can also include some extra data. intent.putExtra("message", "This is my message!"); LocalBroadcastManager.getInstance(this).sendBroadcast(intent);}With the code above, every time the button R.id.button_send is clicked, an Intent is broadcasted and is received by mMessageReceiver in ReceiverActivity.
The debug output should look like this:
01-16 10:35:42.413: D/sender(356): Broadcasting message01-16 10:35:42.421: D/receiver(356): Got message: This is my message!
Here is something similar to @Shiki answer, but from the angle of iOS developers and Notification center.
First create some kind of NotificationCenter service:
public class NotificationCenter { public static void addObserver(Context context, NotificationType notification, BroadcastReceiver responseHandler) { LocalBroadcastManager.getInstance(context).registerReceiver(responseHandler, new IntentFilter(notification.name())); } public static void removeObserver(Context context, BroadcastReceiver responseHandler) { LocalBroadcastManager.getInstance(context).unregisterReceiver(responseHandler); } public static void postNotification(Context context, NotificationType notification, HashMap<String, String> params) { Intent intent = new Intent(notification.name()); // insert parameters if needed for(Map.Entry<String, String> entry : params.entrySet()) { String key = entry.getKey(); String value = entry.getValue(); intent.putExtra(key, value); } LocalBroadcastManager.getInstance(context).sendBroadcast(intent); }}Then, you will also need some enum type to be secure of mistakes in coding with strings - (NotificationType):
public enum NotificationType { LoginResponse; // Others}Here is usage(add/remove observers) for example in activities:
public class LoginActivity extends AppCompatActivity{ private BroadcastReceiver loginResponseReceiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { // do what you need to do with parameters that you sent with notification //here is example how to get parameter "isSuccess" that is sent with notification Boolean result = Boolean.valueOf(intent.getStringExtra("isSuccess")); } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_login); //subscribe to notifications listener in onCreate of activity NotificationCenter.addObserver(this, NotificationType.LoginResponse, loginResponseReceiver); } @Override protected void onDestroy() { // Don't forget to unsubscribe from notifications listener NotificationCenter.removeObserver(this, loginResponseReceiver); super.onDestroy(); }}and here is finally how we post notification to NotificationCenter from some callback or rest service or whatever:
public void loginService(final Context context, String username, String password) { //do some async work, or rest call etc. //... //on response, when we want to trigger and send notification that our job is finished HashMap<String,String> params = new HashMap<String, String>(); params.put("isSuccess", String.valueOf(false)); NotificationCenter.postNotification(context, NotificationType.LoginResponse, params);}that's it, cheers!