A simple implementation of ViewPager, Tabs and Fragments

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.udacity.popularmovies.activities.MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:visibility="visible"
        android:orientation="vertical">
        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:tabMode="fixed" />
        <android.support.v4.view.ViewPager
            android:id="@+id/viewpager"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="@dimen/small_layout_margin"
            android:layout_marginLeft="@dimen/default_layout_margin"
            android:layout_marginRight="@dimen/default_layout_margin"/>
    </LinearLayout>
</LinearLayout>

DetailsFragmentPagerAdapter.java

package com.udacity.popularmovies.adapters;

import android.content.Context;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;

import com.udacity.popularmovies.R;
import com.udacity.popularmovies.fragments.MovieDetailsFragment;
import com.udacity.popularmovies.fragments.MovieReviewsFragment;
import com.udacity.popularmovies.fragments.MovieVideosFragment;

/**
 * Created by jesse on 13/09/18.
 * This is a part of the project adnd-popular-movies.
 */
public class DetailsFragmentPagerAdapter extends FragmentPagerAdapter {

    private Context mContext;
    private static final Integer PAGE_NUMBER = 3;

    /**
     * Create a new {@link DetailsFragmentPagerAdapter} object.
     *
     * @param context is the context of the app
     * @param fragmentManager is the fragment manager that will keep each fragment's state in the adapter
     *           across swipes.
     */
    public DetailsFragmentPagerAdapter(Context context, FragmentManager fragmentManager) {
        super(fragmentManager);
        mContext = context;
    }

    @Override
    public Fragment getItem(int position) {
        if (position == 0) {
            return new MovieDetailsFragment();
        } else if (position == 1){
            return new MovieReviewsFragment();
        } else {
            return new MovieVideosFragment();
        }
    }

    @Override
    public int getCount() {
        return PAGE_NUMBER;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        if (position == 0){
            return mContext.getString(R.string.tab_details);
        } else if (position == 1){
            return  mContext.getString(R.string.tab_reviews);
        } else {
            return mContext.getString(R.string.tab_videos);
        }
    }
}

MainActivity.java

package com.udacity.popularmovies.activities;

import android.support.design.widget.TabLayout;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import com.udacity.popularmovies.R;
import com.udacity.popularmovies.adapters.DetailsFragmentPagerAdapter;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ViewPager viewPager = findViewById(R.id.viewpager);
        DetailsFragmentPagerAdapter fragmentPagerAdapter = new DetailsFragmentPagerAdapter(this, getSupportFragmentManager());
        viewPager.setAdapter(fragmentPagerAdapter);
        TabLayout tabLayout = findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);

    }
}