SettingsActivity.java 文件源码

@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 >= 0
            ? listPreference.getEntries()[index]
            : null);

  } else if (preference instanceof RingtonePreference) {
    // For ringtone preferences, look up the correct display value
    // using RingtoneManager.
    if (TextUtils.isEmpty(stringValue)) {
      // Empty values correspond to 'silent' (no ringtone).
      preference.setSummary(R.string.pref_ringtone_silent);

    } else {
      Ringtone ringtone = RingtoneManager.getRingtone(
          preference.getContext(), Uri.parse(stringValue));

      if (ringtone == null) {
        // Clear the summary if there was a lookup error.
        preference.setSummary(null);
      } else {
        // Set the summary to reflect the new ringtone display
        // name.
        String name = ringtone.getTitle(preference.getContext());
        preference.setSummary(name);
      }
    }

  } else {
    // For all other preferences, set the summary to the value's
    // simple string representation.
    preference.setSummary(stringValue);
  }
  return true;
}