How to detect if changes were made in the preferences?

I have a class that extends PreferenceActivity and shows the preference screen of my app. Is it possible to check if any changes were made to the preferences?

This helps...

http://developer.android.com/reference/android/content/SharedPreferences.OnSharedPreferenceChangeListener.html

Other related post: SharedPreferences.onSharedPreferenceChangeListener not being called consistently

---

public class PreferenceClass extends PreferenceActivity {

	OnSharedPreferenceChangeListener listener;

	public void onCreate(Bundle savedInstanceState) {
		SharedPreferences prefs = this.getSharedPreferences("settings", 0);
		listener = new SharedPreferences.OnSharedPreferenceChangeListener() {

			public void onSharedPreferenceChanged(SharedPreferences prefs, String key) {
				int flag = 1;
			}
		};
		prefs.registerOnSharedPreferenceChangeListener(listener);
		super.onCreate(null);
		addPreferencesFromResource(R.xml.settings);
	}
}

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
    }

}