JAVA的Swing实现点击事件

MyFrame.java

package swing;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.SimpleDateFormat;
import java.util.Date;

public class MyFrame extends JFrame {
    JLabel timeLabel= new JLabel("00:00:00");
    JButton button=new JButton("显示时间");

    public MyFrame(String title){
        super(title);
        //内容面板
        Container contentPane=getContentPane();
        contentPane.setLayout(new FlowLayout());

        //向内容面板添加控件
        contentPane.add(button);
        contentPane.add(timeLabel);
        //创造监听器对象
        //把监听器注册给按钮
        button.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e) {
                //当按钮被点击时，Swing框架会调用监听器的actionPerformed()方法
                System.out.println("按钮被点击....");
                showTime();
            }
        });

    }
    public void showTime(){
        SimpleDateFormat sdf=new SimpleDateFormat("HH:mm:ss");
        String timestr=sdf.format(new Date());
        timeLabel.setText(timestr);
        System.out.println("时间已更新");
    }
}
package swing;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.SimpleDateFormat;
import java.util.Date;

public class MyFrame extends JFrame {
    JLabel timeLabel= new JLabel("00:00:00");
    JButton button=new JButton("显示时间");

    public MyFrame(String title){
        super(title);
        //内容面板
        Container contentPane=getContentPane();
        contentPane.setLayout(new FlowLayout());

        //向内容面板添加控件
        contentPane.add(button);
        contentPane.add(timeLabel);
        //创造监听器对象
        //把监听器注册给按钮
        button.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e) {
                //当按钮被点击时，Swing框架会调用监听器的actionPerformed()方法
                System.out.println("按钮被点击....");
                showTime();
            }
        });

    }
    public void showTime(){
        SimpleDateFormat sdf=new SimpleDateFormat("HH:mm:ss");
        String timestr=sdf.format(new Date());
        timeLabel.setText(timestr);
        System.out.println("时间已更新");
    }
}

SwingDemo.java

package swing;

import javax.swing.*;

public class SwingDemo {
    private static void createGUI(){

        //JFrame指一个窗口，构造方法的参数为窗口标题
        MyFrame frame=new MyFrame("swing demo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //设置窗口的其它参数，如窗口大小
        frame.setSize(400,300);

        //显示窗口
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                createGUI();
            }
        });
    }
}