create fragment in activity

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.test_activity_custom_ui_3);
        addFragment(android.R.id.content,
                DiamondsWalletFragment.newInstance(),
                "DiamondsWalletFragment");
    }

    protected void addFragment(int containerViewId,
                               Fragment fragment,
                               String fragmentTag) {
        getSupportFragmentManager()
                .beginTransaction()
                .add(containerViewId, fragment, fragmentTag)
                .disallowAddToBackStack()
                .commit();
    }