Tab Layout now showing fragments

Hey guys can you help me with this? im newbie im not very good, so here's the thing i've been trying to create tab layout BUT the fragments that i call isnt show up. can you guys help me im really stuck over here. so i use FragmentStateAdapter inside pageradapter

here is my Tab.java

     package com.app.appforum.fragments;
    
    import android.os.Bundle;
    
    import androidx.annotation.Nullable;
    import androidx.appcompat.app.AppCompatActivity;
    import androidx.viewpager2.widget.ViewPager2;
    
    import com.app.appforum.R;
    import com.google.android.material.tabs.TabLayout;
    
    import java.util.Objects;
    
    public class Tab extends AppCompatActivity {
    
        private TabLayout tabLayout;
        private ViewPager2 viewPager2;
    
        @Override
        protected void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.tab);
    
            tabLayout = findViewById(R.id.tab_layout);
            viewPager2 = findViewById(R.id.view_pager);
    
            MyViewPagerAdapter myViewPagerAdapter = new MyViewPagerAdapter(this);
    
            viewPager2.setAdapter(myViewPagerAdapter);
    
            tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
                @Override
                public void onTabSelected(TabLayout.Tab tab) {
                    viewPager2.setCurrentItem(tab.getPosition());
                }
    
                @Override

            public void onTabUnselected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {

            }
        });

        viewPager2.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
            @Override
            public void onPageSelected(int position) {
                super.onPageSelected(position);
                Objects.requireNonNull(tabLayout.getTabAt(position)).select();
            }
        });
    }
}

here is my MyViewPagerAdapter

package com.app.appforum.fragments;

import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentActivity;
import androidx.viewpager2.adapter.FragmentStateAdapter;

public class MyViewPagerAdapter extends FragmentStateAdapter {
    public MyViewPagerAdapter(@NonNull FragmentActivity fragmentActivity) {
        super(fragmentActivity);
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
       switch (position){
           case 1:
               return new VideoFragment();
           case 2:
               return new MateriFragment();
           default:
               return new ForumFragment();
       }
    }

    @Override
    public int getItemCount() {
        return 3;
    }
}

and here is my xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
    tools:context=".fragments.Tab"

    >

    <!-- TODO: Update blank fragment layout -->

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tab_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <com.google.android.material.tabs.TabItem
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/forum" />

        <com.google.android.material.tabs.TabItem
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/video" />

        <com.google.android.material.tabs.TabItem
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/materi" />
    </com.google.android.material.tabs.TabLayout>

    <androidx.viewpager2.widget.ViewPager2
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/view_pager"
        android:layout_below="@+id/tab_layout"/>


</RelativeLayout>

please and thank you.