Question

I’m making a fairly basic game. In my preferences, there’s an option to change the difficulty setting. I’d like to be able to somehow, in the main activity that called it, sense if they’ve changed the difficulty. (And then restart the game)

I’m having difficulty because of how the preference activity is handled asynchronously. If I add logic to check the value before and after sending the intent to my PreferenceActivity (from a menu selection), it really doesn’t work…

Can someone point me in a proper direction as to either how to serialize a chunk of code normally handled asynchronously, or have an idea of how to sense preferences changed? Is there a listener class hidden somewhere?

For posterity’s sake, here’s the code handling the intent and how I’m failing. (snippet, from inside menu onOptionsItemSelected, inside a switch)

case R.id.menuOptions:
    String currentDifficulty = preferences.getString("difficulty","problem!");
    Intent i = new Intent(this, prefs.class);
    startActivity(i);
    if (currentDifficulty.equals(preferences.getString("difficulty","problem!")))
        return true;
    else doNewGame();
    return true;

Answer 1

Android allows you to register a preference changed listener. Here’s a quick example:

public class myClass implements OnSharedPreferenceChangeListener
{
    private SharedPreferences settings;

    settings = PreferenceManager.getDefaultSharedPreferences(this);
    settings.registerOnSharedPreferenceChangeListener(this);

    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key)
    {
       // Process it here
    }
}