MainActivity from CDA10

MainActivity.java

public class MainActivity extends AppCompatActivity {

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

        FragmentManager mFragmentManager = getSupportFragmentManager();

        mFragmentManager.beginTransaction()
                .add(R.id.fragment_container, mMainFragment)
                .commit();
    }
}