"Unsupported type 'PreferenceActivity' in file" Android

Question

I'm still new in Android programming, and I just can't solve this problem. I'm creating a Preference Screen, but at the moment I run the application, I get the following error:

Error:Execution failed for task ':app:mergeDebugResources'.
> Unsupported type 'PreferenceScreen' in file C:\Users\Fidel Sebastián\AndroidStudioProjects\Asteroides\app\src\main\res\values\preferencias.xml

This is the XML file:

    <?xml version="1.0" encoding="utf-8"?>
<resources>
    <PreferenceScreen
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:key="preferencias_principal" >
        <CheckBoxPreference
            android:key="music"
            android:title="Start music"
            android:summary="Select for background music"/>
        <ListPreference
            android:key="graphics"
            android:title="Graphics type"
            android:summary="Choose your graphics type"
            android:entries="@array/graphicstype"
            android:entryValues="@array/graphicsTypeValues"
            android:defaultValue="1"/>
        <EditTextPreference
            android:key="fragments"
            android:title="Number of fragments"
            android:summary="Select for meteor fragments"
            android:defaultValue="3"/>
    </PreferenceScreen>
</resources>

This is the Java file:

package com.example.fidelsebastin.asteroides;


import android.os.Bundle;
import android.preference.PreferenceFragment;

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

I've searched all over the Web, but I still can't find the answer. Any help would be really appreciated. Thanks in advance.

Answer 1

Get rid of the <resource> tags. A PreferenceScreen is not a resource. It should be defined as the top-level object in the XML, as shown in the documentation example:

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:key="preferencias_principal" >
    <CheckBoxPreference
        android:key="music"
        android:title="Start music"
        android:summary="Select for background music"/>
    <ListPreference
        android:key="graphics"
        android:title="Graphics type"
        android:summary="Choose your graphics type"
        android:entries="@array/graphicstype"
        android:entryValues="@array/graphicsTypeValues"
        android:defaultValue="1"/>
    <EditTextPreference
        android:key="fragments"
        android:title="Number of fragments"
        android:summary="Select for meteor fragments"
        android:defaultValue="3"/>
</PreferenceScreen>

Additionally:

1. You need to move the preferences file into res/xml instead of res/values

2. You should pass the identifier for the preferences file into addPreferencesFromResource(), not R.xml.arrays:

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