Question

Java 鼠标监听事件 mouseMoved(MouseEvent)

import java.awt.Color;
import javax.swing.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
public class BtnText1 extends JFrame implements MouseMotionListener
{
private JButton btn;
private JPanel panel=new JPanel();
public void init()
{
btn=new JButton("改变颜色的按钮");
btn.addMouseListener(new MouseAdapter(){
public void mouseEntered(MouseEvent e){
panel.setBackground(Color.blue);
}
public void mouseExited(MouseEvent e){
panel.setBackground(Color.green);
}
public void mouseClicked(MouseEvent e){
if(e.getClickCount()==2)
panel.setBackground(Color.gray);
if(e.getClickCount()==1)
panel.setBackground(Color.black);
}
});
btn.addMouseMotionListener(new MouseAdapter(){
public void mouseDragged(MouseEvent e){}
public void mouseMoved(MouseEvent e){
panel.setBackground(Color.red);
}
});

this.add(panel);
this.setBounds(110,110,200,200);
panel.add(btn);
this.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args)
{
new BtnText1().init();
}
}

上面的代码怎么实现鼠标在按钮上上面移动面板变红

Answer 1

public class BtnText1 extends  JFrame implements MouseMotionListener

不需要实现MouseMotionListener接口，你已经用了addMouseMotionListener方法

MouseAdapter类已经是实现了MouseMotionListener接口的。

改成

public class BtnText1 extends  JFrame

可以运行成功