What is the JavaGUI event listening mechanism?

1. There are objects in an event model: event source, event and listener

2. Event listening mechanism:

• Event source Where the event occurs

• Event What is going to happen

• Event processing The solution for what happened

• Event monitoring Associate the event source with the event

##Usage steps:

• Create a new component (such as JButton)

• Add the component to the corresponding panel (such as JFrame)

• Register a listener to listen for events generated by the event source (For example, using ActionListener to respond to the user clicking a button)

• Define the method for handling events (such as defining the corresponding method in actionPerformed in ActionListener)

Example 1:

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
public class AddActionListener {
    public static void main(String[] args) {
        JFrame jf = new JFrame("AddActionListener");
        jf.setLayout(new FlowLayout(FlowLayout.LEFT));
        jf.setBounds(400, 300, 400, 300);
        JTextArea area=new JTextArea(20,10);
        area.setLineWrap(true);
        JButton jb=new JButton("秃头");
        jb.addActionListener(new AbstractAction() {
            @Override
            public void actionPerformed(ActionEvent e) {
                area.setText("不要熬夜！");
            }
        });
        jf.add(area);
        jf.add(jb);
        jf.setVisible(true);
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

##Example 2:

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
public class AddActionListener {
    public static void main(String[] args) {
        JFrame jf = new JFrame("AddActionListener");
        jf.setLayout(new FlowLayout(FlowLayout.LEFT));
        jf.setBounds(400, 300, 400, 300);
        JTextArea area=new JTextArea(20,10);
        area.setLineWrap(true);
        JButton jb=new JButton("秃头");
        jb.addActionListener(new AbstractAction() {
            @Override
            public void actionPerformed(ActionEvent e) {
                area.append("不要熬夜！");
            }
        });
        jf.add(area);
        jf.add(jb);
        jf.setVisible(true);
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

tips: ActionEvent

is a Class, e is an instance of that class. You can replace e with whatever you like, for example. eventor object

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