How do I call inside the layout activity_main(sw320dp)?

I want to call gray (sw320dp) layout file

Layout:- activity_main(sw320dp)

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate (Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main(sw320dp));
 }
}

from How do I call inside the layout activity_main(sw320dp)?