用Java创建一个窗口

package java123;
import java.util.Scanner;

import java.util.Random;
import java.awt.*;
import javax.swing.*;
public class lyy extends Jframe{
	
	public void create(String title) {
		Jframe jf = new Jframe(title);
		Container container = jf.getContentPane();
		JLabel jl = new JLabel("一个窗口");
		jl.setHorizontalAlignment(SwingConstants.CENTER);
		container.add(jl);
		container.setBackground(Color.white);
		jf.setVisible(true);
		jf.setSize(400,270);
		jf.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
		}
		public static void main(String args[]) {
			new lyy().create("一个窗口");
		}
		
		}