Can't get the PreferenceFragment to work (Comp

问题:

I am getting error when i try to compile my project: "The method add(int, Fragment) in the type FragmentTransaction is not applicable for the arguments (int, FragmentPreferences)". As far as i know, the PreferenceFragment is a Fragment? I am developing for android 4.0 but i have to use android-support-v4 library because my project incluedes also ViewPager. I found this example at http://developer.android.com/guide/topics/ui/settings.html#Fragment:

// Display the fragment as the main content.
        getFragmentManager().beginTransaction()
                .replace(android.R.id.content, new SettingsFragment())
                .commit();

But i can't get it to work.

My code:

case R.id.menu_settings:
    FragmentPreferences prefs = new FragmentPreferences();
    FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
    ft.add(android.R.id.content, prefs);
    ft.commit();
    break;

FragmentPreferences:

public class FragmentPreferences extends PreferenceFragment {
    @Override
    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.preferences);
    }

}

回答1:

That's because PreferenceFragment extends android.app.Fragment, rather than the android.support.v4.app.Fragment that the android.support.v4.app.FragmentTransaction is expecting.

As of yet, there is no official backport of the PreferenceFragment to the support library. However, you can use libraries such as UnifiedPreferences to fill this gap.

回答2:

Check the import statements at the top of your code. Likely one of the classes you are using is from support while the other is not.

回答3:

Here is the unofficial backport of the PreferenceFragment to the support library. Last update was Feb 2015 & it's compatible with lollipop devices. android-support-v4-preferencefragment

import android.support.v4.preference.PreferenceFragment;