gistfile1.java

@Override
    protected void onPause() {
        super.onPause();
        // Unregister the listener whenever a key changes
        getPreferenceScreen().getSharedPreferences()
                .unregisterOnSharedPreferenceChangeListener(this);
    }
 
    @Override
    protected void onResume() {
        super.onResume();
        //update phone preference summary with actual value
        SharedPreferences preferences = getPreferenceScreen().getSharedPreferences();
        phoneNumberPreference.setSummary(preferences.getString(PHONE_NUMBER_PREFERENCE, getResources().getString(R.string.phone_number_desc)));
        preferences.registerOnSharedPreferenceChangeListener(this);
    }

    @Override
    public void onSharedPreferenceChanged(SharedPreferences preferences, String key) {
        //update phone preference summary with actual value
        if(key.equals(PHONE_NUMBER_PREFERENCE)){
            phoneNumberPreference.setSummary(preferences.getString(key, getResources().getString(R.string.phone_number_desc)));
        }
    }