title: How to create a Listener to Preferences changes in Preferences activity?
body: <p>I have Preferences activity in my app that has ListPreference so the user can choose language for the app.</p>
  
  <p>The app displays the new language just after the user close the Preferences activity.</p>
  
  <p>I want to create a listener to the ListPreference so the app will restart when the Listener is triggers (just after the user choose a language/choose item from the ListPreference).</p>
  
  <p>How can I do that?</p>
  
  <p>SettingsActivity:</p>
  
  <pre><code>public class SettingsActivity extends AppCompatPreferenceActivity {
  /**
   * A preference value change listener that updates the preference's summary
   * to reflect its new value.
   */
  private static Preference.OnPreferenceChangeListener sBindPreferenceSummaryToValueListener = new Preference.OnPreferenceChangeListener() {
      @Override
      public boolean onPreferenceChange(Preference preference, Object value) {
          String stringValue = value.toString();
  
          if (preference instanceof ListPreference) {
              // For list preferences, look up the correct display value in
              // the preference's 'entries' list.
              ListPreference listPreference = (ListPreference) preference;
              int index = listPreference.findIndexOfValue(stringValue);
  
              // Set the summary to reflect the new value.
              preference.setSummary(
                      index &gt;= 0
                              ? listPreference.getEntries()[index]
                              : null);
  
          } else {
              // For all other preferences, set the summary to the value's
              // simple string representation.
              preference.setSummary(stringValue);
          }
          return true;
      }
  };
  
  
  /**
   * Binds a preference's summary to its value. More specifically, when the
   * preference's value is changed, its summary (line of text below the
   * preference title) is updated to reflect the value. The summary is also
   * immediately updated upon calling this method. The exact display format is
   * dependent on the type of preference.
   *
   * @see #sBindPreferenceSummaryToValueListener
   */
  private static void bindPreferenceSummaryToValue(Preference preference) {
      // Set the listener to watch for value changes.
      preference.setOnPreferenceChangeListener(sBindPreferenceSummaryToValueListener);
  
      // Trigger the listener immediately with the preference's
      // current value.
      sBindPreferenceSummaryToValueListener.onPreferenceChange(preference,
              PreferenceManager
                      .getDefaultSharedPreferences(preference.getContext())
                      .getString(preference.getKey(), ""));
  }
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setupActionBar();
      setTitle(R.string.action_settings);
  }
  
  /**
   * Set up the {@link android.app.ActionBar}, if the API is available.
   */
  private void setupActionBar() {
      ActionBar actionBar = getSupportActionBar();
      if (actionBar != null) {
          // Show the Up button in the action bar.
          actionBar.setDisplayHomeAsUpEnabled(true);
      }
  }
  
  @Override
  public boolean onMenuItemSelected(int featureId, MenuItem item) {
      int id = item.getItemId();
      if (id == android.R.id.home) {
          if (!super.onMenuItemSelected(featureId, item)) {
              NavUtils.navigateUpFromSameTask(this);
          }
          return true;
      }
      return super.onMenuItemSelected(featureId, item);
  }
  
  /**
   * This method stops fragment injection in malicious applications.
   * Make sure to deny any unknown fragments here.
   */
  protected boolean isValidFragment(String fragmentName) {
      return PreferenceFragment.class.getName().equals(fragmentName)
              || GeneralPreferenceFragment.class.getName().equals(fragmentName);
  }
  
  /**
   * This fragment shows general preferences only. It is used when the
   * activity is showing a two-pane settings UI.
   */
  @TargetApi(Build.VERSION_CODES.HONEYCOMB)
  public static class GeneralPreferenceFragment extends PreferenceFragment {
      @Override
      public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          addPreferencesFromResource(R.xml.pref_general);
          setHasOptionsMenu(true);
  
          // Bind the summaries of EditText/List/Dialog/Ringtone preferences
          // to their values. When their values change, their summaries are
          // updated to reflect the new value, per the Android Design
          // guidelines.
          bindPreferenceSummaryToValue(findPreference("example_text"));
          bindPreferenceSummaryToValue(findPreference(getString(R.string.language_shared_pref_key)));
      }
  
      @Override
      public boolean onOptionsItemSelected(MenuItem item) {
          int id = item.getItemId();
          if (id == android.R.id.home) {
              Intent intent = new Intent(getActivity(), MainActivity.class);
              intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
              getActivity().finish();
              startActivity(intent);
              return true;
          }
          return super.onOptionsItemSelected(item);
      }
  }
  </code></pre>
  
  <p>}</p>
  
  <p>pref_general.xml:</p>
  
  <pre><code>&lt;PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"&gt;
  
  &lt;ListPreference
      android:defaultValue="@string/language_code"
      android:entries="@array/pref_languages_list_titles"
      android:entryValues="@array/pref_languages_list_values"
      android:key="@string/language_shared_pref_key"
      android:negativeButtonText="@null"
      android:positiveButtonText="@null"
      android:title="@string/pref_title_language" /&gt;
  
  &lt;/PreferenceScreen&gt;
  </code></pre>
  
  <p>Thank you!!!</p>