java - 每次单击 JButton 时如何将值增加 1？

Question

我刚刚了解了 ActionListener，我的任务是使用与 JLabel 关联的 JButton 创建一个简单的应用程序int 每次被点击时值增加 1。这是我的编码:

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

class ButtonPanel2 extends JPanel implements ActionListener {

JButton button2;
JLabel secondLabel;

int i = 1;
int total = 0;

ButtonPanel2()
{
    button2 = new JButton("Push");
    add(button2);

    button2.addActionListener(this);

    secondLabel = new JLabel("Button pushes: " + total);
    add(secondLabel);
}

public void actionPerformed(ActionEvent e)
{
    total += i;
}
}

和驱动类:

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

class TestButtonPanel2 {

public static void main(String [] args)
{
    JFrame buttonFrame2 = new JFrame("Button Panel 2");

    ButtonPanel2 panel2 = new ButtonPanel2();

    buttonFrame2.add(panel2);
    buttonFrame2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    buttonFrame2.setSize(400 , 400);
    buttonFrame2.setVisible(true);
}
}

提前致谢! :)

Answer 1

在 ActionListener 中，像这样更新 GUI:

public void actionPerformed(ActionEvent e)
{
    total += i;
    secondLabel.setText("Button pushes: " + total);
}