和「行動非法啓動」「預期」編譯器錯誤

Question

我得到的代碼

行讀取一行4個錯誤「公益行動無效的actionPerformed（ActionEvent的事件）{」被「非法的開始行動「兩次，」預計「兩次。

我將這段代碼從Head First Java書中拷出來，爲什麼heck不會編譯它？

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

你不能在另一個方法中定義一個方法。移動actionPerformed外部go塊

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