How to return values from a java class that extends another class into an Activity

Question

Let's say that I've the following main activity:

public class MwConsoleActivity extends Activity {

    private classChild child = null;    

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        child = new classChild();
    }
}

Then consider the implementation of the class "classChild":

public class MwBondingAgent extends SapereAgent {

    MwBondingAgent(){}

    public void AddEventListener(childAddedEvent event) {

       //Send the data of event back to the main activity

    }
}

I've tried to use IntentServices but was not able to receive the values back to the main activity. What would be the approach I've to take?

Cheers Ali

i'm not sure exactly what you are asking. are you asking how to implement the observer pattern using a listener? — toadzky, Oct 31 '12 at 14:26
Thank you guys for your replies.The solution with design pattern is very clean. But I managed to solve this problem by IntentService and ResultReceiver which is much more better than IntentFilters. The link provided below helped me a lot: http://stackoverflow.com/questions/3028306/download-a-file-with-android-and-showing-the-progress-in-a-progressdialog/3028660#3028660 — don ali, Nov 01 '12 at 18:19

score 2 · Accepted Answer · answered Oct 31 '12 at 14:41

You can use and intentFilter to listen for broadcasts. Add this to the activity:

 IntentFilter intentFilter = new IntentFilter(
                "com.unique.name");
        mReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                //extract our message from intent
                String msg_for_me = intent.getStringExtra("some_msg");
             }
        };
        //registering our receiver
        this.registerReceiver(mReceiver, intentFilter);

In your class add this to the part you want to notify the activity:

Intent i = new Intent("com.unique.name").putExtra("some_msg", "I have been updated!");
this.sendBroadcast(i);

score 1 · Answer 2 · answered Oct 31 '12 at 14:38

1

You should use the observer / listener pattern.

http://www.vogella.com/articles/DesignPatternObserver/article.html

It is one of the most used design patterns when using MVC architecture pattern.

answered Oct 31 '12 at 14:38

Fabian Knapp

1,342
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score 1 · Answer 3 · answered Oct 31 '12 at 14:39

Your question is quite unclear but I think what you are wanting is to implement a callback to your activity. You can do this using an interface.

public class MwConsoleActivity extends Activity implements MwBondingAgent{

    private classChild child = null;    

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        child = new classChild();
    }

    @Override
    public void gotEventData(EventData myEventData) {

        //to whatever you want with myEventData
    }
}

And in your other class.

public class MwBondingAgent extends SapereAgent {

    private MwBondingAgentCallback activityCallback;

    MwBondingAgent(Activity callback){

         activityCallback = callback;
    }

    public void AddEventListener(childAddedEvent event) {

        //Send the data of event back to the main activity
        EventData myEventData = //got some event data;
        //Send it back to activity
        activityCallback.gotEventData(myEventData);
    }

    public interface MwBondingAgentCallback {

        public void gotEventData(EventData myEventData);
    }
}

How to return values from a java class that extends another class into an Activity

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