java内部类

1.heartbeat

2.this.heartbeat

3.People.this.heartbeat

import javax.swing.*;
import java.awt.event.ActionEvent;

//通过GUI编程，理解匿名内部类的真是使用场景
public class Test3 {
    public static void main(String[] args) {
        //1.创建窗口
        JFrame win = new JFrame("登录界面");
        JPanel panel = new JPanel();//垫个桌布
        win.add(panel);
        //2.创建按钮对象
        JButton btn = new JButton("登录");

        //注意：匿名内部类的使用
        btn.addActionListener(new AbstractAction() {
            @Override
            public void actionPerformed(ActionEvent e) {
                JOptionPane.showMessageDialog(win,"点我一下hahahah");
            }
        });
//可以简化代码！！！：
// btn.addActionListener((e)->JOptionPane.showMessageDialog(win,"点我一下hahahah"));


        //3.把按钮对象添加到窗口上
        panel.add(btn);
        //4.展示窗口
        win.setSize(400,300);
        win.setLocationRelativeTo(null);
        win.setVisible(true);
    }

}