How to detect if changes were made in the preferences?

Do

SharedPreferences.OnSharedPreferenceChangeListener spChanged = new                           SharedPreferences.OnSharedPreferenceChangeListener() {            @Override    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences,            String key) {        // your stuff here    }};

In your PreferenceActivity, ie make it a member of your PreferenceActivity class and then do registerOnSharedPreferenceChangeListener(spChanged) in the PreferenceActivity.onCreate() method.

That's what I do and I never have a problem.

Else it's your conditional checking in the listener that is at fault. Post the code.

EDIT:

From the code you posted, you should make prefs a class member variable so it has a global scope.

And do prefs = PreferenceManager.getDefaultSharedPreferences(getApplicationContext()); instead of getSharedPreferences because you haven't created that file.

To create a file you need to use PreferenceManager. To get a PreferenceManager, use Activity.getPreferenceManager().

In your PreferenceActivity class, implement the SharedPreferences.OnSharedPreferenceChangeListener interface. Add the required onSharedPreferenceChanged method to your class and register it in the onCreate.

See sample code here:

public class MyPreferences extends PreferenceActivity implements SharedPreferences.OnSharedPreferenceChangeListener {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        addPreferencesFromResource(R.xml.fw_preferences); //deprecated        PreferenceManager.getDefaultSharedPreferences(this).registerOnSharedPreferenceChangeListener(this);    }    @Override    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {        // handle the preference change here    }}