import java.net.*;
import java.io.*;
import javax.swing.*;
import java.util.regex.*;
import java.util.*;

import java.awt.*;
import java.util.List;

public class main {
  public static void main(String[] args) {
    JFrame frame = new JFrame("A JavaX Frame");
    

JPanel panel = new JPanel();
    
    frame.add(panel);
    frame.setBounds(100, 100, 500, 400);
    frame.setVisible(true);
    exitOnFrameClose(frame);
  }

  static void exitOnFrameClose(JFrame frame) {
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }

}