Android communication between Activities without onActivityResult

Question

In an App I am currently working on I am facing a problem regarding the communication between Activities.
Basicly I have a UI-Component, which is similar to a Combobox. However, the list of the possible values for this component has to be openend in a new Activity.
So when you clicked the component, a new Activity is opened, using startActivityForResult.
When you select the new value, it is put inside a Bundle and returned to the previous Activity. I then need to use the onActivityResult-method to get the selected value and set it to the component.
That means, that every Activity that uses this component needs to override onActivityResult and refresh the component with the new value.
What I want instead is, that the component takes care about all this stuff and you only have to register a Listener, just like you do it for a TextView and similar components.
But at the moment I just can't find a good way to do that, as the communication is tightly bound to the Activity and I just can't get the result of the Activity outside the onActivityResult.
Does anyone know a good solution for this problem?

Answer 1

Solution to this- use EventBus and post sticky event on it. By doing so you don't have to override onActivityResult.

The workflow will be as following: - Create event object with your data - Remove all sticky events of the same type from the Bus - post new values by .sendSticky() method.

That event will be around until something remove it from the bus - start another activity - in this activity override method, subscribing to that event type, in it: a) take and process event with your argument b) remove it from the bus - subscribe to the bus (second Activity) in onResume() method - unsubscribe from the bus in .onPause() method

The point is, that this allow you to seamlessly handle lifecycle of second Activity, and you can subscribe/unsubscribe to the bus in base class

Answer 2

What about using BroadCastReceiver?

Basically you send a broadcast and every activity that is registered to receive that broadcast will receive that broadcast will receive the message in onReceive

First of all declare in the manifesto what you are going to listen for, something like:

   <receiver android:name=".TestBroadCast”>
      <intent-filter>
         <action android:name="io.test.TEST"/>
      </intent-filter>
   </receiver>

Than simply extend BroadCastReceiver

public class TestBroadCastReceiver extends BroadcastReceiver {

   @Override
   public void onReceive(Context context, Intent intent) {
      //TODO: Handle the Intent received.

}

Example of how to send a broadcast:

   public static final String INTENT_ACTION = "io.test.TEST";
   public static final String INTENT_EXTRA  = "someData";

   Intent intent = new Intent();
   intent.setAction(INTENT_ACTION);
   intent.putExtra(INTENT_EXTRA,"test");
   sendBroadcast(intent);

And you will get the Intent and than you can handle it as you wish :)!

UPDATE ~ Registering from code instead of manifesto

To avoid registering the service from the Manifesto you can do it from the code, with a code similar to the following listing:

IntentFilter intentFilter = new IntentFilter("io.test.TEST");
TestBroadCastReceiver mReceiver = new TestBroadCastReceiver();
context.registerReceiver(mReceiver, intentFilter);

P.S. I suggest you using LocalBroadcastReceiver if you don't need other applications to be able to send results insted of the common BroadcastReceiver for security reasons

Answer 3

You can implement Observer Design Pattern, the better implementation of that are BroadcastReceiver and a Library which implement event bus design Otto

Answer 4

Hello @Alex Shutov was right Try this https://github.com/greenrobot/EventBus http://greenrobot.org/eventbus/

Answer 5

Use EventBus here is the link https://github.com/greenrobot/EventBus only 3 steps and yes it is 3rd PartyLibrary. its very light should not affect your app size as well

Answer 6

Generally for such scenario I will keep the data in Main Activity as static data and use and update them in other activities.

For example you can declare and populate these 2 variables in Main Activity (i.e. MainActivity)

public static ArrayList arrayList ;

public static SparseBooleanArray sparseBooleanArray ;

now all other activities while populating list values, they can populate from array list using name MainActivity.arrayList. When user select or unselect a value only sparseBooleanArray will be updated with a boolean value.

while populating values first time in arrayList and sparseBooleanArray , ensure to use same index so they will be in sync

arrayList.add(1,"List Item 1") ;

sparseBooleanArray.put(1,false ) ; // represent selected value for List Item 1

In case you have plan to use this functionality for multiple activities, arraylist will remain same, however there will be one SparseBooleanArray for each activity to store activity wise selected values.