Luke Swain Luke Swain - 6 months ago 17
Java Question

OnSharedPreferenceChangeListener Won't Work?

I am trying to change the application background color, and the font type via theme when a preference is changed in the prefs area.

So far I have the preferences working but when I put the listener in, it just does not get called. I am testing using toasts to see if it appears.

My Code:

package alertssystem.lsa13tafeproj.lsa13.resistorcalculator;

import android.app.ActionBar;
import android.content.Intent;
import android.content.SharedPreferences;
import android.graphics.Color;
import android.os.Bundle;
import android.preference.PreferenceActivity;
import android.preference.PreferenceFragment;
import android.preference.PreferenceManager;
import android.widget.RelativeLayout;
import android.widget.Toast;

import java.util.prefs.PreferenceChangeEvent;
import java.util.prefs.PreferenceChangeListener;

public class Prefs extends PreferenceActivity
{

@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
getFragmentManager().beginTransaction().replace(android.R.id.content, new PreferencesFragment()).commit();
}



@Override
public void onBackPressed()
{
Intent intent = new Intent(getApplicationContext(), MainActivity.class);
startActivity(intent);
}

public static class PreferencesFragment extends PreferenceFragment
{
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.prefs);
}
}
}


There is no changeListener in above code as none of the solutions I found worked, can someone please tell me how I can implement this into this.

The user clicks on the ListPreference and it has the 2 options I have inserted, but nothing happens when new option is selected.

Answer

This works for me:

public class MyPreferenceFragment extends PreferenceFragment implements
    OnSharedPreferenceChangeListener {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.prefs);
        PreferenceManager.getDefaultSharedPreferences(getActivity()).registerOnSharedPreferenceChangeListener(this);
    }

    @Override
    public void onDestroy() {
        PreferenceManager.getDefaultSharedPreferences(getActivity()).unregisterOnSharedPreferenceChangeListener(this);
        super.onDestroy();
    }

    @Override
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
        // Toast
    }
}

Make sure you register your listener before changing the pref, and not unregistering it until you do.