Using Tabbed Layout with ViewPager

MainActivity.java

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

public class MainActivity extends AppCompatActivity {

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

        ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);

        CategoryAdapter adapter = new CategoryAdapter(this, getSupportFragmentManager());

        assert viewPager != null;
        viewPager.setAdapter(adapter);

        TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);

        assert tabLayout != null;
        tabLayout.setupWithViewPager(viewPager);
    }
}