java - JButton - 如何连接？

Question

我在网上找到了这段代码并对其进行了修改，但它停止工作了。我认为这与我添加 Jpanel 时有关，但我所做的与 JPanel 配合效果最好。如何使 if 语句执行的操作中的事件起作用？

    import java.awt.GridLayout;
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    import java.util.*;

    import javax.swing.*;

    public class GUI extends JFrame implements ActionListener {

    static JPanel panel = new JPanel(new GridLayout(5, 5, 1, 1));

    public GUI() {
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        //setSize(100, 100);
        //setLocation(100, 100);



        //Button 1
        JButton button1 = new JButton("1");
        button1.addActionListener(this);
        panel.add(button1);

        //Button 2
        JButton button2 = new JButton("2");
        button2.addActionListener(this);
        panel.add(button2);

        //Button 3
        JButton button3 = new JButton("3");
        button3.addActionListener(this);
        panel.add(button3);

        //Button 2
        JButton button4 = new JButton("4");
        button4.addActionListener(this);
        panel.add(button4);

        //Button 2
        JButton button5 = new JButton("5");
        button5.addActionListener(this);
        panel.add(button5);

        //Button 2
        JButton button6 = new JButton("6");
        button6.addActionListener(this);
        panel.add(button6);

        //Button 2
        JButton button7 = new JButton("7");
        button7.addActionListener(this);
        panel.add(button7);

        //Button 2
        JButton button8 = new JButton("8");
        button8.addActionListener(this);
        panel.add(button8);

        //Button 2
        JButton button9 = new JButton("9");
        button9.addActionListener(this);
        panel.add(button9);



        panel.setVisible(true);
    }

    public static void main(String[] args) {
        new GUI();
        JFrame f = new JFrame("Calc");
        f.setContentPane(panel);
        f.setSize(1000, 1000);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setVisible(true);

    }

    ArrayList numbers = new ArrayList();
    @Override
    public void actionPerformed(ActionEvent e) {
        String command = e.getActionCommand();

        if (command.equals("button1")) {
            myMethod();
            numbers.add(1);
            System.out.println("1");
        }
        if (command.equals("button1")) {
            numbers.add(2);
            System.out.println("2");
        }
    }

    public void myMethod() {
        JOptionPane.showMessageDialog(this, "Hello, World!!!!!");
        System.out.println("Hey");
    }
}

Answer 1

您需要将actionPerformed部分更改为:

@Override
public void actionPerformed(ActionEvent e) {
     String command = e.getActionCommand();

        if (command.equals("1")) {
            myMethod();
            numbers.add(1);
            System.out.println("1");
        }
        if (command.equals("2")) {
            numbers.add(2);
            System.out.println("2");
        }

}

在这里，当单击按钮时，您的 e.getActionCommand() 将给出构造函数字符串。即“1”、“2”、“3”等等

reference