java - "Illegal Start of action"和 "; expected"编译器错误

Question

我在一行代码中遇到了 4 个错误

“public action void actionPerformed(ActionEvent event){”行获得“Illegal start of action”两次和“;预期”两次。

我从 Head First Java 书中复制了这段代码，为什么它不能编译？

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

public class SimpleGui1 implements ActionListener{
    Jbutton button;

    public static void main (String [] args) {
        SimpleGui1 gui = new SimpleGui1();
        gui.go();
    }

    public void go(){
        JFrame frame = new JFrame();
        button = new JButton("Click");

        button.addActionListener(this);

        frame.getContentPane().add(button);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 300);
        frame.setVisible(true);


        public void actionPerformed(ActionEvent event){
            button.setText("I've been clicked.");
        } //close actionPerformed
    } //close go()

}

Answer 1

您不能在另一个方法中定义一个方法。将 actionPerformed 移到 go block

之外

 public void go(){
        JFrame frame = new JFrame();
        button = new JButton("Click");

        button.addActionListener(this);

        frame.getContentPane().add(button);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 300);
        frame.setVisible(true);


} //close go()



public void actionPerformed(ActionEvent event){
            button.setText("I've been clicked.");
} //close actionPerformed