How to use PreferenceScreen of Androidx

Now the whole answer:

1. Add this line to your App-Gradle: implementation 'androidx.preference:preference:1.1.1' or implementation 'androidx.preference:preference-ktx:1.1.1' for Kotlin. And sync Gradle. Create a Directory named xml in res Folder.

2. Create in this directory an XML-File with your prefered name for example main_preferences. Root Element must be androidx.preference.PreferenceScreen.

3. Fill XML-File with your settings for example:

<?xml version="1.0" encoding="utf-8"?>
<androidx.preference.PreferenceScreen  xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="match_parent"
    android:layout_width="match_parent">
    <androidx.preference.SwitchPreference
        android:defaultValue="true"
        android:key="example_switch"
        android:summary="Turn this option on or off"
        android:title="Settings option" />
</androidx.preference.PreferenceScreen>

4. Create somewhere in the folder com.???.??? a java file for example named MainSettingsFragment. Superclass (means <Classname> extends <Superclass>) must be PreferenceFragmentCompat and override onCreatePreferences. You can copy this code:

import android.os.Bundle; 
import androidx.preference.PreferenceFragmentCompat;
import com.???.???.R;

public class <YourClassname> extends PreferenceFragmentCompat {
    @Override
    public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
        // Load the preferences from an XML resource
        setPreferencesFromResource(R.xml.<yourXmlFilename>, rootKey);
    }
}

5. Next, there are two options to implement the PreferencesSreen in your .

The beautiful and best way is, it to implement it per code on creation. Add in your SettingsActivty a FrameLayout and give it an ID for example fl_main_settings:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_height="match_parent"
    android:layout_width="match_parent"
    android:id="@+id/<!-- yourID -->">

</FrameLayout>

And in your Activity Code add really on the top of the onCreate method this:

package com.???.???;
import android.graphics.drawable.ColorDrawable;
import android.os.Bundle;
import android.text.Html;
import android.view.MenuItem;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.text.HtmlCompat;

import com.???.???.MainSettingsFragment;
public class SettingsActivity extends AppCompatActivity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.<SettingsActivityXML(with the FrameLayout)>);

        //If you want to insert data in your settings
        <YourSettingsFragmentClass> settingsFragment = new <YourSettingsFragmentClass>();
        settingsFragment. ...
        getSupportFragmentManager().beginTransaction().replace(R.id.<YourFrameLayout>,settingsFragment).commit();
        
        //Else
        getSupportFragmentManager().beginTransaction().replace(R.id.<YourFrameLayout>,new <YourSettingsFragmentClass>()).commit();
    }

Or you implement a Fragment in your SettingsActivityXml. But I don't recommend this ,because starting the activity takes a few seconds:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:baselineAligned="false">

    <fragment
        android:tag="frag"
        android:name="com.quickme.musicme.Fragments.MainSettingsFragment"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"/>
</LinearLayout>

That's it have fun.