Android ViewPager Fragments Won't display

I am trying to add tablayout/viewpager in the middle of my page below a carouselview I have added. However, the tabs show up but I can't display the actual fragments.

content_main.xml File

<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:paddingBottom="0dp"
        android:paddingLeft="0dp"
        android:paddingRight="0dp"
        android:paddingTop="0dp"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        tools:context="com.test.MainActivity"
        tools:showIn="@layout/app_bar_main">

        <com.syapps.carouselview.CarouselView
            android:id="@+id/carouselView"
            android:layout_width="match_parent"
            android:layout_height="300dp"
            app:fillColor="#FFFFFFFF"
            app:pageColor="#00000000"
            app:radius="6dp"
            app:slideInterval="10000"
            app:strokeColor="#FF777777"
            app:strokeWidth="1dp" />



        <!--Tabs-->
        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@color/colorPrimary"
            app:tabMode="scrollable"/>

        <android.support.v4.view.ViewPager
            android:id="@+id/mainViewPager"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>


    </LinearLayout>
</ScrollView>

Fragment_main.xml

<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"
    tools:context="com.test.MainFragment">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="@string/hello_blank_fragment" />

</LinearLayout>

MainActivity.java

public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        //Main carousel View
        carouselView = (CarouselView) findViewById(R.id.carouselView);
        carouselView.setPageCount(mainImages.length);

        carouselView.setImageListener(imageListener);

        //Tabs
        TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.addTab(tabLayout.newTab().setText("Buy & Sell"));
        tabLayout.addTab(tabLayout.newTab().setText("Pets"));
        tabLayout.addTab(tabLayout.newTab().setText("Swap / Trade"));
        tabLayout.addTab(tabLayout.newTab().setText("Real Estate (For Rent)"));
        tabLayout.addTab(tabLayout.newTab().setText("Real Estate (For Sale)"));
        tabLayout.addTab(tabLayout.newTab().setText("Vacation Rentals"));
        tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);

        final ViewPager viewPager = (ViewPager) findViewById(R.id.mainViewPager);
        final MainFragmentPagerAdapter adapter = new MainFragmentPagerAdapter
                (getSupportFragmentManager());
        viewPager.setAdapter(adapter);
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
        tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());
            }

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

            }

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

            }
        });
        tabLayout.setTabTextColors(ContextCompat.getColorStateList(this, R.color.tab_selector));
        tabLayout.setSelectedTabIndicatorColor(ContextCompat.getColor(this, R.color.indicator));
    }
}

MainFragmentPagerAdapter.java

package com.test;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;

public class MainFragmentPagerAdapter extends FragmentStatePagerAdapter {

    public MainFragmentPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0:
                retu new MainFragment();
            case 1:
                retu new MainFragment();
            case 2:
                retu new MainFragment();
            case 3:
                retu new MainFragment();
            case 4:
                retu new MainFragment();
            case 5:
                retu new MainFragment();
            default:
                retu null;
        }
    }

    @Override
    public int getCount() {
        retu 6;
    }
}

MainFragment.Java

package com.test;

        import android.os.Bundle;
        import android.support.v4.app.Fragment;
        import android.view.LayoutInflater;
        import android.view.View;
        import android.view.ViewGroup;

public class MainFragment extends Fragment {
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        retu inflater.inflate(R.layout.fragment_main, container, false);
    }
}