程序包括简单地向面板添加按钮,当单击按钮时,屏幕应变为指定按钮的颜色。基本上我需要更改蓝色按钮做同样的事情,但是有一个匿名的内部类,我觉得我有点在正确的轨道上,但我得到一长串的错误。我已经看过许多匿名内部类的例子,我相信我正在编写代码,但是有很多错误与编译器无法找到符号有关,我不完全理解。任何帮助将不胜感激,因为我已经为此工作了2天,我希望能在本周修复它。这是我的代码:(很多东西都被注释掉了,所以我可以一次关注一个按钮)
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
这是我试图添加匿名内部类的地方:
class Blue
{
public void start()
{
ActionListener listener = new Blue();
}
public class Blue implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
Object source = evt.getSource();
Color color = getBackground();
color = Color.blue;
setBackground(color);
repaint();
}
}
}
class ButtonPanel extends JPanel //implements ActionListener
{
private JButton yellowButton;
private JButton blueButton;
private JButton redButton;
private JButton greenButton;
public ButtonPanel()
{
//yellowButton = new JButton("Yellow");
//redButton = new JButton("Red");
blueButton = new JButton("Blue");
//greenButton = new JButton("Green");
//add(yellowButton);
//add(redButton);
add(blueButton);
//add(greenButton);
//yellowButton.addActionListener(this);
blueButton.addActionListener(listener);
//greenButton.addActionListener(this);
/*class Red
{
public void red()
{
ActionListener listener = new ActionListener();
redButton.addActionListener(listener);
}
class turnRed implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
setBackground(Color.red);
repaint();
}
}
}*/
}
/*public void actionPerformed(ActionEvent evt)
{
Object source = evt.getSource();
Color color = getBackground();
if (source == yellowButton) color = Color.yellow;
else if (source == blueButton) color = Color.blue;
else if (source == redButton) color = Color.red;
else if (source == greenButton) color = Color.green;
setBackground(color);
repaint();
}
}
class ButtonFrame extends JFrame
{
public ButtonFrame()
{
setTitle("ButtonTest");
setSize(300, 200);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.add(new ButtonPanel());
}
}
public class ButtonTest
{
public static void main(String[] args)
{
JFrame frame = new ButtonFrame();
frame.setVisible(true);
}
}
答案 0 :(得分:1)
不使用listener
变量,而是创建(新创建的)匿名内部类的实例。这就是它的完成方式:
blueButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
Object source = evt.getSource();
Color color = getBackground();
color = Color.blue;
setBackground(color);
repaint();
}
});