CODEWITHSUNDEEP
android
Rhendar
Rhendar

Reputation: 450

Back button stuck in endless loop?

My app is currently stuck in an endless loop with the physical back button. The program is set up to load a splash screen and then transition to a main menu. Once at the main menu the user can switch to another activity of their choice. For example: The new game activity. Once the user is at the new game activity I want them to be able to hit the back button and have it take them to the main menu. Once back at the main menu, if they hit the back button again I would like it to exit the game.

This is what I am using for each activity:

public boolean onKeyDown(int keyCode, KeyEvent event) {

    if ((keyCode == KeyEvent.KEYCODE_BACK)) { 
        startActivity(new Intent(NewGameActivity.this, MenuActivity.class));
    }
    return super.onKeyDown(keyCode, event); 
}

It works properly and takes the user back to the main menu without a problem. But if the user hits the back button again once at the main menu it will take them to the screen they just escaped from. So it just loops back to the previous screen every time.

This is how the main menu is set up:

public boolean onKeyDown(int keyCode, KeyEvent event) {

    if ((keyCode == KeyEvent.KEYCODE_BACK)) { 
        stopService(new Intent(MenuActivity.this, BGMusicService.class));
        MenuActivity.this.finish();
    }
    return super.onKeyDown(keyCode, event); 
}

If I press the back button as soon as the main menu loads the first time it will work properly and close the game. It only messes up if I've hit the back button previously to get from one screen to the main menu.

Update:

Okay that kind of worked. When I hit the back button at the main screen the music stops and it acts like it's trying to close the app but it flashes back to the main screen again. I have to hit it twice every time.

Upvotes: 4

Views: 2544

Answers (3)

Cat
Cat

Reputation: 67502

First (from comments) add return true; within the if statements (to indicate that you have handled the event), like so:

// Main menu code
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) { 
        stopService(new Intent(MenuActivity.this, BGMusicService.class));
        MenuActivity.this.finish();
        return true; // Add me!
    }
    return super.onKeyDown(keyCode, event); 
}

Additionally, I believe because you're "starting" the menu activity again, you have to clear the back stack (the order of activities used so far) before opening it. You should be able to achieve this using Intent.FLAG_ACTIVITY_CLEAR_TOP (or maybe Intent.FLAG_ACTIVITY_CLEAR_TASK). Something like this:

// Other activity code
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        Intent menuIntent = new Intent(NewGameActivity.this, MenuActivity.class);
        menuIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); // Add me!
        startActivity(menuIntent);
        return true; // Add me, too!
    }
    return super.onKeyDown(keyCode, event); 
}

Upvotes: 1

seaplain
seaplain

Reputation: 771

You haven't called finish() in your other activities so when you call finish() on the menu it just closes itself and the other activity is exposed

Upvotes: 0

Andrea Bresolin
Andrea Bresolin

Reputation: 186

You should call finish() inside the onKeyDown method of your activities so your current activity is actually removed from the stack.

Something like this should work:

public boolean onKeyDown(int keyCode, KeyEvent event)
{
  if (keyCode == KeyEvent.KEYCODE_BACK)
  { 
    startActivity(new Intent(NewGameActivity.this, MenuActivity.class));
    finish();
  }

  return super.onKeyDown(keyCode, event); 
}

Upvotes: 2

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