Android Overriding Onbackpressed()

Android Overriding onBackPressed()

Yes. Only override it in that one Activity with

@Override
public void onBackPressed()
{
     // code here to show dialog
     super.onBackPressed();  // optional depending on your needs
}

don't put this code in any other Activity

override onBackPressed from interface

You shouldn't represent behavior by interface method, you should represent it by whole interface.

public interface OnBackPressedListener {
    void onBackPressedEvent()
}

And then, you should attach this behavior to the activity/fragment/view root.
For example:

public class MyActivity extends Activity implements OnBackPressedListener {

    // Initialize your activity's fields
    
    private boolean isTaskRoot() {
    // implement your task root method
    }

    @Override
    public void onBackPressed() { // This method is provided by activity "from the box".
        onBackPressedEvent();
    }

    @Override
    public void onBackPressedEvent() {
        if(isTaskRoot()) {
            final Dialog dialog = new Dialog(this);
            dialog.setContentView( R.layout.are_you_sure );
            dialog.getWindow().setBackgroundDrawable( new ColorDrawable( Color.TRANSPARENT ) );
        
            if (!this.isFinishing()) {
                dialog.show();
            }
        }   
    }
}

Note that your onBackPressedListener interface should NOT depend on any other methods, behaviors. Its main purpose is to provide an ability to mark the class as the class, which can react to onBackPressed event.

One of the possible usages is to inherit your fragments from onBackPressedListener and then call their onBackPressedEvent methods when parent Activity is notified that back button was pressed.

@Override
public void onBackPressed() {
    // ...
    if (currFragment instanceof onBackPressedListener) {
        currFragment.onBackPressedEvent();
    }
    // ...
}

UPD: If you want to provide ready-to-use behavior for all classes inheriting onBackPressedListener you can use default keyword to create default interface method.

public interface onBackPressedListener() {
    boolean isTaskRoot()

    default void onBackPressedEvent() {
        // Your implementation. 
        // It should not contain calls of methods, which are not presented by this interface. 
        if (isTaskRoot()) // ...
    }
}

OR you can create BaseActivity class, in which you will override onBackPressedEvent from interface

public class BaseActivity extends Activity implements OnBackPressedListener { 
    @Override
    public void onBackPressed() {
    ...
    }
}

And then you inherit your activities from it
public class MyActivity extends BaseActivity { ... }

Android - How To Override the Back button so it doesn't Finish() my Activity?

Remove your key listener or return true when you have KEY_BACK.

You just need the following to catch the back key (Make sure not to call super in onBackPressed()).

Also, if you plan on having a service run in the background, make sure to look at startForeground() and make sure to have an ongoing notification or else Android will kill your service if it needs to free memory.

@Override
public void onBackPressed() {
   Log.d("CDA", "onBackPressed Called");
   Intent setIntent = new Intent(Intent.ACTION_MAIN);
   setIntent.addCategory(Intent.CATEGORY_HOME);
   setIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
   startActivity(setIntent);
}

Android onBackPressed for all activities

Create a single activity with onBackPressed overrided:

public class OnBackPressedActivity extends Activity {
    @Override
    public void onBackPressed() {
        // do stuff
    }
}

And then in your code use not extends Activity, but rather extends OnBackPressedActivity

Android - How to override onBackPressed method but still use default animation?

At the end of that method you have to call "super.onBackPressed()" to execute the normal behavior.

Override onBackPressed() method. Back button has to be clicked twice to quit the Activity

When you do this:

startActivity(new Intent(this, Menu.class));

This starts a new instance of Menu. You want to return to the existing instance of Menu. To do that, you need this:

Intent intent = new Intent(this, Menu.class));
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | 
                Intent.FLAG_ACTIVITY_SINGLE_TOP);
startActivity(intent);

This tells Android that you want to go back to the existing instance of Menu.

Overriding onBackPressed in other Classes

If you want, for example, show a Toast every time user presses a back button and on every screen, you have two options:

1. Implement onBackPressed method in every activity and call some utility class to do that, for example Toasts.showMessage().
2. You can inherit every activity from your BaseActivity where you can override onBackPressed method and show toast there.

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