Question

I have an Android application that uses a class that extends the Activity class, let’s call it MyActivity. In that class I have a handler that handles various things. Now the activity that extends MyActivity class should be able to expand these things, that is it must be able to handle other things than MyActivity.

Here’s an example of what I want:

This is my modified Activity class that has a handler:

class MyActivity extends Activity {
    protected Hander myActivityHandler = new Handler()
    {
        @Override
        public void handleMessage(Message msg) {
            switch(msg.what)
            {
            case CASE_1:
                // do stuff
                break;
            case CASE_2:
                // do other stuff
                break;
            }
        }
    }
}

And here’s the class that extends that class and I want to add more cases to the handler:

class MySuperSpecialActivity extends MyActivity {
    // add/override cases of inherited myActivityHandler handler
}

I don’t know if it’s even possible, there’s probably a better way to achieve this functionality, but that’s how I started my code and a MyActivity class was necessary as it’s used a lot.

Answer 1

You may consider to implement Handler.Callback in your Activity:

public class MainActivity extends Activity implements Handler.Callback {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Handler handler = new Handler(this);
    }

    @Override
    public boolean handleMessage(Message msg) {
        // Handle your message here
        return false;
    }    
}

Inherit new Activity from this Activity and overwrite “handleMessage”:

public class AnotherActivity extends MainActivity {
    @Override
    public boolean handleMessage(Message msg) {
        super.handleMessage(msg);
        return super.handleMessage(msg);
    }

}