程序代码：

import java.awt.Dimension;
import java.awt.Insets;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.Random;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;


public class ClickMe extends JFrame{
    private JButton button;
    
    public ClickMe() {
        super("小游戏");
        getContentPane().setLayout(null);
        button= new JButton("点我");
        button.setMargin(new Insets(-2,-1,-2,-1));
        button.setBounds(30, 30, 30, 30);
        button.addActionListener(
                new ActionListener(){
                    public void actionPerformed(ActionEvent event){
                        JOptionPane.showMessageDialog(null, "你点中我啦！");
                    }
                }
                );
        add(button);
        
        addMouseMotionListener(
                new MouseAdapter(){
                    Random rand = new Random();
                    public void mouseMoved(MouseEvent event){
                        int xdot = rand.nextInt(400);
                        int ydot = rand.nextInt(400);
                        button.setLocation(xdot, ydot);
                    }
                }
                );
        setSize(400,400);
        setResizable(false);
        //屏幕居中
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        Dimension frameSize = getSize();
        setLocation((screenSize.width - frameSize.width)/2,(screenSize.height - frameSize.height)/2);
        
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }
    public static void main(String[] args) {
        new ClickMe();
    }
}