Question

java 在一个面板中使用paint方法画了个图片，在另一个类中添加监听，对之前面板中添加图片，需要怎么实现

Answer 1

class Demo{
    Image image;
    JPanel panel;
    //...
    Demo(){
        panel=new JPanel(){
            @override
            public void paint(Graphics g){
                if(null!=image){
                    g.drawImage(image, ...);
                }
                super.paint(g);
            }
        };
        //...
        JButton button=new JButton("添加图片");
        getContentPan().add(button);
        button.addActionListener(new ActionListener(){
            @override
            public void actionPerformed(ActionEvent e){
                if(null==image){
                    image=Toolkit. ... .getImage(...);
                }
                else{
                    image=null;
                }
                panel.repaint();
            }
        });
        //...
    }
    //...
}