When apply onBackPressed in Fragment which extends dialog Fragment

Question

I want to implement onBackPressed in fragment which extends a DialogFragment. But when overriding it gives an error that "method does not override its superclass".
How to implement it?
See here for a chunk of the code.

See here for backpressed code

Answer 1

Follow this. Its awesome example to implement onBackPressed() functionality on Fragment by using Abstract Class.

1) Create an Abstract Class -

import android.app.Fragment;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;

public abstract class BackableFragment extends Fragment implements View.OnKeyListener {

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        view.setFocusableInTouchMode(true);
        view.requestFocus();
        view.setOnKeyListener(this);
    }

    @Override
    public boolean onKey(View v, int keyCode, KeyEvent event) {
        if (event.getAction() == KeyEvent.ACTION_UP) {
            if (keyCode == KeyEvent.KEYCODE_BACK) {
                onBackButtonPressed();
                return true;
            }
        }

        return false;
    }

    public abstract void onBackButtonPressed();
}

2) Implement the Abstract Class to your Fragment -

public class FragmentChannels extends BackableFragment {

    ...

    @Override
    public void onBackButtonPressed() {
        if (doTheThingRequiringBackButtonOverride) {
            // do the thing
        } else {
            getActivity().onBackPressed();
        }
    }

    ...
}

Thats it. Reference

Answer 2

Try this

private boolean exit = false;
  /* your full actvivty */


@Override
 public void onBackPressed() {
  if (exit) {
            super.onBackPressed();
            return;
        } else {
            Toast.makeText(this, "Press Back again to Exit.", Toast.LENGTH_SHORT).show();
            exit = true;
            new Handler().postDelayed(new Runnable() {
                @Override
                public void run() {
                    exit = false;
                }
            }, 2000);
        }
    }

Answer 3

When using fragments in your app, individual FragmentTransaction objects may represent context changes that should be added to the back stack. For example, if you are implementing a master/detail flow on a handset by swapping out fragments, you should ensure that pressing the Back button on a detail screen returns the user to the master screen. To do so, call addToBackStack() before you commit the transaction:

// Works with either the framework FragmentManager or the
// support package FragmentManager (getSupportFragmentManager).
getSupportFragmentManager().beginTransaction()
                           .add(detailFragment, "detail")
                           // Add this transaction to the back stack
                           .addToBackStack()
                           .commit();

If your application updates other user interface elements to reflect the current state of your fragments, such as the action bar, remember to update the UI when you commit the transaction. You should update your user interface after the back stack changes in addition to when you commit the transaction. You can listen for when a FragmentTransaction is reverted by setting up an FragmentManager.OnBackStackChangedListener:

getSupportFragmentManager().addOnBackStackChangedListener(
        new FragmentManager.OnBackStackChangedListener() {
            public void onBackStackChanged() {
                // Update your UI here.
            }
        });

Answer 4

@Swati as per your comment, you want to exit your current dialog as well as current activity. The dialog is another level of window that display on top of your current activity. The DialogFragment is just a shell which hold the actual dialog and manage the state such as device rotate.

The dialog itself has consume the keyevent include backpress as well. So there is no such backpress method on DialogFragment.

I would recommend you to get the dialog after it was created see here , override this method and let super class create the dialog then set dismiss listener to it. In the dismiss listener callback you can finish your activity and it will return to the previous activity. You can also use getDialog method which should work the same.

Answer 5

Hi maybe I'm too late for the right anwser but this works for me

@Override
public void onResume() {
    super.onResume();


    if (getView() != null)
        getView().setFocusableInTouchMode(true);

    getView().requestFocus();
    getView().setOnKeyListener((v, keyCode, event) -> {
        if (event.getAction() == KeyEvent.ACTION_DOWN) {
            if (keyCode == KeyEvent.KEYCODE_BACK) {
                //TODO: Put here your action or method 
                return true;
            }
        }
        return false;
    });
}

Answer 6

You have code in you dialog fragment key listener method

  dialog!!.setOnKeyListener { _ , keyCode, event ->
        keyCode == KeyEvent.KEYCODE_BACK
    }

By this even on back press click dialog fragment wont dismiss But you have to set dialog property as

 dialog?.setCancelable(false)
    dialog?.setCanceledOnTouchOutside(false)