package zhongyu;

import javax.swing.*;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;


public class Demo extends JDialog{
	public Demo() {
		Container c = getContentPane();
		
		c.add(new JLabel("博主是帅哥！！！"));
		setVisible(true);
		Random r =new Random();
		int x = r.nextInt(500);
		int y = r.nextInt(500);
		setBounds(x,y,280,280);
	}
	
	public static void main(String[] args) {
		JFrame f = new JFrame("父窗体");
		f.setBounds(100,100,620,620);
		Container c = f.getContentPane();
		JButton btn = new JButton("弹出一个秘密");
		c.add(btn);
		f.setVisible(true);
		f.setDefaultCloseOperation(EXIT_ON_CLOSE);
		c.setLayout(new FlowLayout());
		btn.addActionListener(new ActionListener() {
			
			
			public void actionPerformed(ActionEvent e) {
				new Demo();
			}
		});
	}
}

由于 setBound()四个参数分别对应两个坐标，宽和高

我们只需要调用Random库

来实现随机坐标的分配即可。