Hide item in Android preferences menu

Question

my Application has a Preferences menu. there are 2 checkbox: "Enable Music", and "Show Hints". What I want is, There is Music List will show if check "Enable Music", else Music list will not enable. My code is:

boolean OPT_MUSIC_DEF = true;
protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      addPreferencesFromResource(R.xml.settings);
      if (!PreferenceManager.getDefaultSharedPreferences(this).getBoolean(OPT_MUSIC, OPT_MUSIC_DEF)){
                Preference list = findPreference("music_list");
                list.setEnabled(false);
         }
}

There is no error, but it work incorrect. When I unCheck "Enable Music" Music List did not hide right away, I must back and go to menu again to see Music List is hide. Any way to make it hidden directly after uncheck "Enable Music" item? thank for help me!

Answer 1

There is built in functionality to do exactly what you're trying to do. In your preferences.xml file set the dependency for the music_list preference to depend on the music_enable preference.

For example:

    <android.preference.CheckBoxPreference
        android:key="music_enable"
        android:defaultValue="false"
        android:title="Enable Music"
        />

    <android.preference.ListPreference
        android:key="music_list"
        ...
        android:dependency="music_enable"
        />

Whenever the user checks the "music_enable" check box the "music_list" will be enabled; when they uncheck the "music_enable" check box the "music_list" will be disabled.

Answer 2

If you want to force refresh the appearance of your preference, just do:

Preference myPref = findPreference("mypref");
myPref.setDefaultValue((int)(Math.random()*1000); // you can also backup the value before and reset it after if you need to keep a default value

Not the perfect solution, but it will surely force Android to refresh your preferences.

BTW, I tried Paul-Jan solution but unluckily it didn't work, it seems that onContentChanged() will just do nothing if no value is changed.

Answer 3

确保禁用首选项后立即调用onContentChanged（） 。