第八章习题※答案(4)

private JButton btn1, btn2; private int j=0,k=0; private MyPanel p1; public MyFrame() { }

public void actionPerformed(ActionEvent e) { if(e.getSource()==btn1) j++; if(e.getSource()==btn2) k++;

p1.setJK(j,k); p1.repaint();

btn1=new JButton(\确定\ btn2=new JButton(\取消\p1 = new MyPanel();

p1.setBackground(Color.white); JPanel p2 = new JPanel(); p2.add(btn1); p2.add(btn2);

this.getContentPane().setLayout(new BorderLayout()); this.getContentPane().add(p1,BorderLayout.CENTER); this.getContentPane().add(p2,BorderLayout.SOUTH);

btn1.addActionListener(this); btn2.addActionListener(this);

}

public static void main(String[] args) { }

MyFrame myFrame = new MyFrame(); myFrame.setTitle(\

myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); myFrame.setSize(400,300); myFrame.setVisible(true);

}

class MyPanel extends JPanel {

private int j=0,k=0; public void setJK(int j,int k) { this.j = j;

}

this.k = k;

}

public void paintComponent(Graphics g) { super.paintComponent(g); }

g.setColor(Color.green);

g.drawString(\你点击了\\\确定\\\按钮 \次\g.setColor(Color.red);

g.drawString(\你点击了\\\取消\\\按钮 \次\

15.编写一个图形界面应用程序，其中包含一个按钮。当鼠标移到按钮上时，隐藏按钮；当鼠标离开按钮时，显示按钮。

（知识点考察：设置监听器，进行事件处理） import javax.swing.*; import java.awt.*;

import java.awt.event.*; import java.io.*;

public class TestMouseEvent extends JPanel{ JButton button; TestMouseEvent(){

button=new JButton(\ add(button);

button.addMouseListener(new MouseAdapter(){ public void mouseEntered(MouseEvent e){ button.setVisible(false); }

public void mouseExited(MouseEvent e){ button.setVisible(true); } }); }

public static void main(String[] args){

JFrame frame=new JFrame(\ frame.addWindowListener(new CloseWindow()); frame.getContentPane().add(new TestMouseEvent()) ; frame.pack(); frame.setVisible(true); } }

class CloseWindow extends WindowAdapter{ public void windowClosing(WindowEvent e){ System.exit(0); } }