MainActivity

public class MainActivity extends MvpAppCompatActivity {

    private LinearLayout mLoc;
    private ImageView mIVBack, mIVFilt;
    private ToastUtil mToast;

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

        mToast = new ToastUtil();
        mLoc = tb.findViewById(R.id.tbLoc);
        mIVBack = tb.findViewById(R.id.ivTbBack);
        mIVFilt = tb.findViewById(R.id.ivFilter);
        showFragment(new MainFragment());
    }

    public void showFragment(Fragment fragment){

        getSupportFragmentManager()
                .beginTransaction()
                .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
                .replace(R.id.container, fragment)
                .commit();

    }
}