Core Java 2书里的一例题,在我的机子上运行出现了这样的错误
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ButtonTest {
public static void main(String[] args){
ButtonFrame frame=new ButtonFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
class ButtonFrame extends JFrame{
public ButtonFrame(){
setTitle( "ButtonTest ");
setSize(DEFAULT_WIDTH,DEFAULT_HEIGHT);
ButtonPanel panel=new ButtonPanel();
add(panel);
}
public static final int DEFAULT_WIDTH=300;
public static final int DEFAULT_HEIGHT=200;
}
class ButtonPanel extends JPanel{
public ButtonPanel(){
JButton yellowButton=new JButton( "Yellow ");
JButton blueButton=new JButton( "Blue ");
JButton redButton=new JButton( "Red ");
add(yellowButton);
add(blueButton);
add(redButton);
ColorAction yellowAction=new ColorAction(Color.YELLOW);
ColorAction blueAction=new ColorAction(Color.BLUE);
ColorAction redAction=new ColorAction(Color.RED);
yellowButton.addActionListener(yellowAction);
blueButton.addActionListener(blueAction);
redButton.addActionListener(redAction);
}
private class ColorAction implements ActionListener{
public ColorAction(Color c){
backgroundColor=c;
}
public void actionPerformed(ActionEvent event){
setBackground(backgroundColor);
}
private Color backgroundColor;
}
}
用javac就能成功编译,但用java运行的时候就会出现在的错误:
Exception in thread "main " java.lang.Error: Do not use ButtonFrame.add() use But
tonFrame.getContentPane().add() instead
at javax.swing.JFrame.createRootPaneException(JFrame.java:465)
at javax.swing.JFrame.addImpl(JFrame.java:491)
at java.awt.Container.add(Container.java:307)
at ButtonFrame. <init> (ButtonTest.java:16)
at ButtonTest.main(ButtonTest.java:6)
[解决办法]
异常
不要用ButtonFrame.add()
用ButtonFrame.getContentPane().add()
[解决办法]
Do not use ButtonFrame.add() use But
tonFrame.getContentPane().add() instead
