Mine

import javax.swing.*;

public class window extends JFrame{
	public window(){
		
		final int WINDOW_WIDTH = 350;
		final int WINDOW_HEIGHT = 250;
		
		//JFrame window = new JFrame();
		
		setTitle("Window");
		
		setSize(WINDOW_WIDTH, WINDOW_HEIGHT);
		
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		setVisible(true);
	}
}