java swing 按钮上字在鼠标划过消失，是怎么回事。

[十秒耿直拆包选手]

rt
corejava volume 中第八章例子，怎么我的鼠标放到按钮上字就没有了。

/**
 * 
 */
package chap08;

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

/**
 * @version 1.0
 * @date 2014-06-28
 * @author jowei
 *
 */
public class ButtonFrame extends JFrame {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		//Frame1 f = new Frame1();
		Frame2 f = new Frame2();
		//Frame3 f = new Frame3();
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		//f.pack();
		f.setVisible(true);
	}
}

/**
 * descr:private local class implements ActionListener.
 * @version 1.0 2014-07-03
 * 
 * */
class Frame1 extends JFrame {
	
	public Frame1() {
		
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
		
		buttonPanel = new JPanel();
		buttonPanel.setLayout(new FlowLayout());
		add(buttonPanel, BorderLayout.EAST);
		
		JButton btnYellow = new JButton(BG_YELLOW);
		JButton btnBlue = new JButton(BG_BLUE);
		JButton btnRed = new JButton(BG_RED);
		
		buttonPanel.add(btnYellow);
		buttonPanel.add(btnBlue);
		buttonPanel.add(btnRed);
		
		ColorAction yellowAction = new ColorAction(Color.YELLOW);
		ColorAction bluewAction = new ColorAction(Color.BLUE);
		ColorAction redAction = new ColorAction(Color.RED);
		
		btnYellow.addActionListener(yellowAction);
		btnBlue.addActionListener(bluewAction);
		btnRed.addActionListener(redAction);
	}
	
    private class ColorAction implements ActionListener {
		
		public ColorAction(Color c) {
			
			this.backgroundColor = c;
		}
		
		@Override
		public void actionPerformed(ActionEvent e) {
			
			buttonPanel.setBackground(this.backgroundColor);
		}
		
		private Color backgroundColor;
	}
	
	private JPanel buttonPanel;
	private static final int DEFAULT_WIDTH = 300;
	private static final int DEFAULT_HEIGHT = 200;
	
	private static final String BG_YELLOW = "Yellow";
	private static final String BG_BLUE = "Blue";
	private static final String BG_RED = "Red";
}

/**
 * descr:anonymous inner class implements ActionListener.
 * */
class Frame2 extends JFrame {
	
	public Frame2() {
		
		//setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
		
		buttonPanel = new JPanel();
		buttonPanel.setLayout(new FlowLayout());
		add(buttonPanel, BorderLayout.CENTER);
		
		makeButton(Frame2.BG_YELLOW, Color.YELLOW);
		makeButton(Frame2.BG_BLUE, Color.BLUE);
		makeButton(Frame2.BG_RED, Color.RED);
	}
	
	private void makeButton(String name, final Color bgColor) {
		
		JButton btn = new JButton(name);
		buttonPanel.add(btn);
		
		btn.addActionListener(new ActionListener() {
			
			@Override
			public void actionPerformed(ActionEvent e) {
				
				buttonPanel.setBackground(bgColor);
			}
		});
	}
	
	@Override
	public void setPreferredSize(Dimension preferredSize) {
		
		super.setPreferredSize(new Dimension(DEFAULT_WIDTH, DEFAULT_HEIGHT));
	}
	
	@Override
	public Dimension getPreferredSize() {
		
		return new Dimension(DEFAULT_WIDTH, DEFAULT_HEIGHT);
	}
	
	@Override
	public void setMinimumSize(Dimension minimumSize) {
		
		super.setMinimumSize(new Dimension(DEFAULT_WIDTH, DEFAULT_HEIGHT));
	}
	
	private JPanel buttonPanel;
	private static final int DEFAULT_WIDTH = 300;
	private static final int DEFAULT_HEIGHT = 200;
	
	private static final String BG_YELLOW = "Yellow";
	private static final String BG_BLUE = "Blue";
	private static final String BG_RED = "Red";
}

class Frame3 extends JFrame {
	
	public Frame3() {
		
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
		
		buttonPanel = new JPanel();
		buttonPanel.setLayout(new FlowLayout());
		add(buttonPanel, BorderLayout.CENTER);
		
		Action yellowAction = new ColorAction(Frame3.BG_YELLOW, Color.YELLOW);
		Action blueAction = new ColorAction(Frame3.BG_BLUE, Color.BLUE);
		Action redAction = new ColorAction(Frame3.BG_RED, Color.RED);
		Action testAction = new ColorAction("test", Color.RED);
		
		makeButton(yellowAction);
		makeButton(blueAction);
		makeButton(redAction);
		makeButton(testAction);
	}
	
	private void makeButton(Action act) {
		
		JButton button = new JButton(act);
		
		buttonPanel.add(button);
	}
	
	private class ColorAction extends AbstractAction {
		
		public ColorAction(String name, Color color) {
			
			putValue(Action.NAME, name);
			putValue(ColorAction.COLOR_NAME, color);
			putValue(Action.SHORT_DESCRIPTION, "Set panel color to " + name.toLowerCase());
		}
		
		@Override
		public void actionPerformed(ActionEvent e) {
			
			Color c = (Color) getValue(ColorAction.COLOR_NAME);
			buttonPanel.setBackground(c);
		}
		
		private final static String COLOR_NAME = "color";
	}
	
	private JPanel buttonPanel;
	private static final int DEFAULT_WIDTH = 300;
	private static final int DEFAULT_HEIGHT = 200;
	
	private static final String BG_YELLOW = "Yellow";
	private static final String BG_BLUE = "Blue";
	private static final String BG_RED = "Red";
}

[十秒耿直拆包选手]

少加了一句： 将每个Frame中的setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);注释掉就不会出现字不显示的情况，只是此时初始化的Frame最小化。

[十秒耿直拆包选手]

结贴，应该是java自己的bug，换到jdk7_up15就正常显示了。

[天命王子]

引用 2 楼 weiweiqiao 的回复:

结贴，应该是java自己的bug，换到jdk7_up15就正常显示了。

你确定是jdk7的bug吗？为什么我换到jdk8还是不正常显示呢？

[一只修炼千年的狐]

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