Settings.java 文件源码

@Override
public void onPause() {
    // uncheck pin if pin is invalid
    SharedPreferences sharedPreferences = getPreferenceManager().getSharedPreferences();
    boolean pinEnabled = sharedPreferences.getBoolean("pref_pin_enabled", false);
    if(pinEnabled) {
        String pin = sharedPreferences.getString("pref_pin", null);
        if(pin == null || pin.length() < 4) {
            // pin invalid: uncheck
            ignoreChanges = true;
            ((SwitchPreference) findPreference("pref_pin_enabled")).setChecked(false);
            ignoreChanges = false;
        }
    }

    getPreferenceManager().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this);
    super.onPause();
}