一个小问题,大哥门帮忙看一下，跪谢，10分 必给

Question

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class FrameDemo extends JFrame implements ActionListener{ /**
 * @param args
 */
public FrameDemo(){
 JButton button1=  new JButton();
 JButton button2 = new JButton();
 JButton button3 = new JButton();
 JButton button4 = new JButton();
 JButton button5 = new JButton();
 JButton button6 = new JButton();

Container container = getContentPane();

container.setLayout(new FlowLayout());

JPanel p1 = new JPanel();
p1.setLayout(new FlowLayout());
getContentPane().add(button1);
getContentPane().add(button2);
getContentPane().add(button3);
getContentPane().add(button4);
getContentPane().add(button5);
getContentPane().add(button6);

JPanel p2 = new JPanel();
p2.setLayout(new FlowLayout());


container.add(p1);
container.add(p2);

button1.addActionListener(this);
button2.addActionListener(this);
button3.addActionListener(this);
button4.addActionListener(this);
button5.addActionListener(this);
button6.addActionListener(this);
}


public void actionPerformed(ActionEvent e)
{

if(e.getSource()== button1)
System.out.println("Button1 is clicked");

if(e.getSource()== button2)
System.out.println("Button1 is clicked");

if(e.getSource()== button3)
System.out.println("Button1 is clicked");

if(e.getSource()== button4)
System.out.println("Button1 is clicked");

if(e.getSource()== button5)
System.out.println("Button1 is clicked");

if(e.getSource()== button6)
System.out.println("Button1 is clicked");


}

public static void main(String[] args) {
// TODO Auto-generated method stub
FrameDemo frame = new FrameDemo();

frame.setSize(300,400);
frame.setVisible(true);
//frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);


}}
为什么报错，说
public void actionPerformed(ActionEvent e)
{

if(e.getSource()== button1)
System.out.println("Button1 is clicked");

if(e.getSource()== button2)
System.out.println("Button1 is clicked");

if(e.getSource()== button3)
System.out.println("Button1 is clicked");

if(e.getSource()== button4)
System.out.println("Button1 is clicked");

if(e.getSource()== button5)
System.out.println("Button1 is clicked");

if(e.getSource()== button6)
System.out.println("Button1 is clicked");


}

中的buttoni(i=1,2.....)不能解释

Answer 1

作用域的问题，你这些button都在构造函数里声明定义的，在actionPerformed方法里当然是不可见的
把这些作为类的私有变量就可以了

Answer 2

完整的程序如下:(我运行过了,应该是你要的效果把)
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class FrameDemo extends JFrame implements ActionListener{ /**
 * @param args
 */
                static JButton button1=  new JButton("button1");
static JButton button2 = new JButton("button2");
static JButton button3 = new JButton("button3");
static JButton button4 = new JButton("button4");
static JButton button5 = new JButton("button5");
static JButton button6 = new JButton("button6");
public FrameDemo(){
 

Container container = getContentPane();

container.setLayout(new FlowLayout());

JPanel p1 = new JPanel();
p1.setLayout(new FlowLayout());
getContentPane().add(button1);
getContentPane().add(button2);
getContentPane().add(button3);
getContentPane().add(button4);
getContentPane().add(button5);
getContentPane().add(button6);

JPanel p2 = new JPanel();
p2.setLayout(new FlowLayout());


container.add(p1);
container.add(p2);

button1.addActionListener(this);
button2.addActionListener(this);
button3.addActionListener(this);
button4.addActionListener(this);
button5.addActionListener(this);
button6.addActionListener(this);
}


public void actionPerformed(ActionEvent e)
{

if(e.getSource()== button1)
System.out.println("Button1 is clicked");

if(e.getSource()== button2)
System.out.println("Button2 is clicked");

if(e.getSource()== button3)
System.out.println("Button3 is clicked");

if(e.getSource()== button4)
System.out.println("Button4 is clicked");

if(e.getSource()== button5)
System.out.println("Button5 is clicked");

if(e.getSource()== button6)
System.out.println("Button6 is clicked");


}

public static void main(String[] args) {
// TODO Auto-generated method stub
FrameDemo frame = new FrameDemo();

frame.setSize(300,400);
frame.setVisible(true);
//frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);


}}

Answer 3

楼上的把域定义为static其实不是一件好事吧?

Answer 4

晕，自己改了改，编译过去了，是个GUI布局的问题~~~~~~~~~对了，谁能给我详细介绍一下作用域的作用？？我一直搞不太懂