android实现片段中的侦听器

Question

I am new in Android development. I want to add a listener in my fragment which upon button click will send a message. I need to listen to this in my main fragment class so that my activity can access this main fragment and process the message. I also need to remove the listener in my main fragment. So how do I implement this?

EDIT

I have MyFragment

sendMessage(message) is a method in MyFragment which has a button click. Need to implement listener here?

In MainFragment How to handle this sendMessage event here and send to MAinActivity

The flow is like MyFragment(childfragment) -> MAinFragment -> MainActivity

Answer 1

In your fragment class, say MyFragment.java create an interface

public interface MyFragmentInterfacer{
    void onButtonClick(String msg);
}
MyFragmentInterfacer fragmentInterfacer;

//Override this function as below to set fragmentInterfacer
@Override
public void onAttach(Context context){
    fragmentInterfacer = (MyFragmentInterfacer)context;
}

and where you want to invoke this function

myButton.setOnClickListener(new View.OnClickListener(){
    @Override
    public void onClick(View v){
        if(fragmentInterfacer != null){
             fragmentInterfacer.onButtonClick("This is my Message");
        }
    }
});

Then in your main activity where you want to get this message, implement this interface

public class MainActivity implements MyFragment.MyFragmentInterfacer{
.
.
}

and then implement the interface function in MainActivity

@Override
public void onButtonClick(String msg){
    //Do something with this message
}

To remove this listener, use

fragmentInterfacer = null;

in your fragment class when you want to disable this listener.

Or you can remove the onClickListener from button

myButton.setOnClickListener(null);

or disable clicking on button

myButton.setClickable(false);

Answer 2

For communicating between your activity and fragments you can interfaces. The idea is basically to define an interface inside a given fragment and let the activity implement that interface.

Once it has implemented that interface, you could do anything you want in the method it overrides.

To help you with some code level details, you can refer http://simpledeveloper.com/how-to-communicate-between-fragments-and-activities/

Hope this will help!