我正在尝试编写一个Java程序，当您单击JFrame中的某个元素时，JLabel的背景会发生变化。从事件调用时，事件处理方法调用以更改背景的函数不起作用，但是只要您在某个地方调用该方法而不依赖于任何事件，它就会起作用。有没有人知道如何改变MouseRelease事件的背景，因为使用这样的事件处理方法不起作用？
private void MouseReleaseEvent(java.awt.event.MouseEvent evt) {
// Do some random stuff, like a println.
// This println works as a normal println statement should.
System.out.println("Hello World!");
// Now let's try the method that changes the background.
// This method will not work within this event handler, but trying it outside
// of it does work.
changeBackground();
}
编辑：根据所有试图帮助我的人的请求，我已将NetBeans项目工作区上传到FileDropper的zip文件中，您可以下载here。您会注意到，当我从主类调用该方法时，它会闪烁另一个图像并返回到我想要的当前图像，但是当您松开鼠标点击“播放”时，它不会调用它，即使这应该。您可以随意尝试使用代码。
编辑2：由于还要求我为那些不想下载工作区的人发布代码，这里是：
Simon.java
package simon;
public class Simon {
public static void main(String[] args) {
// Load all of the other class files into this main class.
SimonGUI SimonGUI = new SimonGUI();
// For some reason, setting the background color doesn't work when we
// try doing it within the GUI development environment, but it works
// here, so that's what we are going to do.
SimonGUI.getContentPane().setBackground(new java.awt.Color(0, 0, 0));
// Make the form visible to the user. It is now ready for use.
SimonGUI.setVisible(true);
SimonGUI.playBackPattern();
}
}
SimonGUI.java *
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package simon;
import java.awt.Component;
import java.text.NumberFormat;
import java.util.ArrayList;
import java.util.Random;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;
/**
*
* @author Administrator
*/
public class SimonGUI extends javax.swing.JFrame {
// Declare class level variables.
boolean aboutTextVisible = false;
boolean mainMenuVisible = true;
boolean userResponseAllowed = false;
private Component frame;
/**
* Creates new form SimonGUI
*/
public SimonGUI() {
initComponents();
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
lblPlayButton1 = new javax.swing.JLabel();
lblPlayButton = new javax.swing.JLabel();
lblSimonBoard = new javax.swing.JLabel();
lblPlayButton1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/simon/resources/MenuPlay.png"))); // NOI18N
lblPlayButton1.setName("lblPlayButton"); // NOI18N
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setTitle("Simon");
setBackground(new java.awt.Color(0, 0, 0));
setMaximumSize(new java.awt.Dimension(600, 600));
setMinimumSize(new java.awt.Dimension(600, 600));
setName("frmSimon"); // NOI18N
setPreferredSize(new java.awt.Dimension(600, 600));
setResizable(false);
getContentPane().setLayout(null);
lblPlayButton.setIcon(new javax.swing.ImageIcon(getClass().getResource("/simon/resources/MenuPlay.png"))); // NOI18N
lblPlayButton.setCursor(new java.awt.Cursor(java.awt.Cursor.HAND_CURSOR));
lblPlayButton.setName("lblPlayButton"); // NOI18N
lblPlayButton.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseReleased(java.awt.event.MouseEvent evt) {
lblPlayButtonMouseReleased(evt);
}
});
getContentPane().add(lblPlayButton);
lblPlayButton.setBounds(150, 20, 317, 58);
lblPlayButton.getAccessibleContext().setAccessibleName("lblPlayerButton");
lblSimonBoard.setIcon(new javax.swing.ImageIcon(getClass().getResource("/simon/resources/Original.PNG"))); // NOI18N
lblSimonBoard.setToolTipText("");
lblSimonBoard.setFocusable(false);
lblSimonBoard.setHorizontalTextPosition(javax.swing.SwingConstants.CENTER);
lblSimonBoard.setName("lblSimon"); // NOI18N
getContentPane().add(lblSimonBoard);
lblSimonBoard.setBounds(-1, 93, 600, 497);
lblSimonBoard.getAccessibleContext().setAccessibleName("lblSimon");
getAccessibleContext().setAccessibleName("frmSimon");
getAccessibleContext().setAccessibleDescription("");
pack();
}// </editor-fold>
private void lblPlayButtonMouseReleased(java.awt.event.MouseEvent evt) {
// This handles the start of Simon gameplay.
toggleBoard();
playBackPattern();
}
public void toggleBoard() {
// Handles toggling between the main menu and the simon board.
if (mainMenuVisible == true)
{
// Board is visible, let's toggle it off.
lblPlayButton.setBounds(700, 700, 317, 58);
mainMenuVisible = false;
lblSimonBoard.setIcon(new javax.swing.ImageIcon(getClass().getResource("/simon/resources/Original.PNG")));
}
else
{
// Board is not visible, let's toggle it on.
lblPlayButton.setBounds(120, 140, 317, 58);
mainMenuVisible = true;
lblSimonBoard.setIcon(new javax.swing.ImageIcon(getClass().getResource("/simon/resources/SimonBackground.PNG")));
}
}
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
/*
* Set the Nimbus look and feel
*/
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/*
* If Nimbus (introduced in Java SE 6) is not available, stay with the
* default look and feel. For details see
* http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(SimonGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(SimonGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(SimonGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(SimonGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/*
* Create and display the form
*/
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new SimonGUI().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JLabel lblPlayButton;
private javax.swing.JLabel lblPlayButton1;
public javax.swing.JLabel lblSimonBoard;
// End of variables declaration
public void flashColor(int colorID) {
// Flash one of the colors. The value of the color that we are going to
// flash is passed here, and the color is flashed.
// Pause for a fraction of a second before blinking the color. In case
// something goes wrong during the pause, we have an error which we hope
// to never use that will catch the program's weakness.
try {
Thread.sleep(250);
} catch (InterruptedException ex) {
JOptionPane.showMessageDialog(frame,"A fatal error has caused Simon to stop working.","Simon • Fatal Error",JOptionPane.ERROR_MESSAGE);
System.exit(0);
}
// Flash the respective color.
if(colorID == 1) {
// Flash Red
lblSimonBoard.setIcon(new javax.swing.ImageIcon(getClass().getResource("/simon/resources/Red.PNG")));
}
else if(colorID == 2){
// Flash Green
lblSimonBoard.setIcon(new javax.swing.ImageIcon(getClass().getResource("/simon/resources/Green.PNG")));
}
else if (colorID == 3) {
// Flash Yellow
lblSimonBoard.setIcon(new javax.swing.ImageIcon(getClass().getResource("/simon/resources/Yellow.PNG")));
}
else {
// Flash Blue
lblSimonBoard.setIcon(new javax.swing.ImageIcon(getClass().getResource("/simon/resources/Blue.PNG")));
}
// Wait for a fraction of a second before we return to the regular
// board. In case something bad happens here while we pause, we have an
// error message that we hope will never be used.
try {
Thread.sleep(250);
lblSimonBoard.setIcon(new javax.swing.ImageIcon(getClass().getResource("/simon/resources/Original.PNG")));
} catch (InterruptedException ex) {
JOptionPane.showMessageDialog(frame,"A fatal error has caused Simon to stop working.","Simon • Fatal Error",JOptionPane.ERROR_MESSAGE);
System.exit(0);
}
}
public void userResponseEnabled(boolean responsePermitted) {
// Toggles the class-level variable "userResponseAllowed", which
// controls if the user can click on the buttons on the Simon board and
// give a response.
// Pass the value to the class-level variable.
userResponseAllowed = responsePermitted;
}
// "Actual Game Code"
int score = 0;
ArrayList pattern = new ArrayList();
int playerColor = 0;
int y = 0;
boolean correct = true;
private SimonGUI SimonGUI;
int certainColor = 1;
int numberOfColors = 0;
public void playBackPattern() {
// Normally, the playBackPattern() method has more than just this line,
// but for demo purposes, this line is all that is needed.
flashColor(4);
}
}
*部分代码是使用NetBeans的Swing GUI设计器附件自动生成的。
答案 0 :(得分：2)
JLabel默认是透明的，必须更改setOpaque()
我不知道方法MouseReleaseEvent是什么，不要重定向Swing事件（在某些情况下是可行的，但对于newbee则不是这样），
MouseListener中实施的标准事件为mousePressed, mouseReleased, mouseEntered, mouseExited, mouseClicked
阅读Oracle教程How to Write a Mouse Listener，了解工作示例和各种不同的事件类型
答案 1 :(得分：1)
根据示例代码，至少有两件事我可以令人担忧
null布局。每个系统都是独一无二的，具有自己的字体，屏幕分辨率和DPI属性。为了克服这个问题，并且使编写复杂的用户界面变得更容易，这些界面不仅适用于不同的计算机，而且适用于不同的操作系统，因此开发了布局管理API。强烈建议您查看Laying Out Components Within a Container Thread.sleep。Swing是一个单线程框架。也就是说，要求对UI的所有交互和修改都发生在事件调度线程的上下文中。阻止此线程的任何操作都将阻止它处理绘制请求等。
这意味着当您执行Thread.sleep时，您将阻止EDT更新UI，直到退出方法为止...
我能想到的最简单的解决方案是使用javax.swing.Timer。以下是一个演示这个想法的简单例子。
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class SimpleSimon {
public static void main(String[] args) {
new SimpleSimon();
}
public SimpleSimon() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JLabel board;
private Timer timer;
private int flashCount;
private int flashColor;
private Image[] colors;
private Image original;
public TestPane() {
colors = new Image[4];
try {
colors[0] = ImageIO.read(getClass().getResource("/resources/Blue.PNG"));
colors[1] = ImageIO.read(getClass().getResource("/resources/Green.PNG"));
colors[2] = ImageIO.read(getClass().getResource("/resources/Red.PNG"));
colors[3] = ImageIO.read(getClass().getResource("/resources/Yellow.PNG"));
original = ImageIO.read(getClass().getResource("/resources/Original.PNG"));
} catch (Exception e) {
e.printStackTrace();
}
setLayout(new BorderLayout());
JButton btn = new JButton("Play");
board = new JLabel();
board.setHorizontalAlignment(JLabel.CENTER);
board.setVerticalAlignment(JLabel.CENTER);
add(board);
timer = new Timer(250, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if (flashCount == 0) {
board.setIcon(new ImageIcon(colors[flashColor]));
} else {
board.setIcon(new ImageIcon(original));
timer.stop();
}
flashCount++;
}
});
timer.setRepeats(true);
add(btn, BorderLayout.SOUTH);
btn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
flashCount = 0;
flashColor = (int)Math.round(Math.random() * 3);
timer.restart();
}
});
}
@Override
public Dimension getPreferredSize() {
return new Dimension(650, 400);
}
}
}
基本上，我会更改您的playBackPattern方法以启动javax.swing.Timer，如果您愿意，可以调用您的flashColor方法，例如......
有关详细信息，请参阅Concurrency in Swing。
更新了“回拨”功能
这提供了一个提供回调功能的基本示例，这样当动画停止时，它将回调指定的对象。
就个人而言，我本来希望稍微有点不同，但是这个例子太复杂了......
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class SimpleSimon {
public static void main(String[] args) {
new SimpleSimon();
}
public SimpleSimon() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JLabel board;
private Timer timer;
private int flashCount;
private int flashTimes;
private int flashColor;
private Image[] colors;
private Image original;
private AnimationCallBack callBack;
public TestPane() {
colors = new Image[4];
try {
colors[0] = createImage(Color.BLUE);
colors[1] = createImage(Color.GREEN);
colors[2] = createImage(Color.RED);
colors[3] = createImage(Color.YELLOW);
original = createImage(Color.WHITE);
} catch (Exception e) {
e.printStackTrace();
}
setLayout(new BorderLayout());
board = new JLabel();
board.setHorizontalAlignment(JLabel.CENTER);
board.setVerticalAlignment(JLabel.CENTER);
add(board);
timer = new Timer(250, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if (flashCount < flashTimes) {
if (flashCount % 2 == 0) {
board.setIcon(new ImageIcon(colors[flashColor]));
} else {
board.setIcon(new ImageIcon(original));
}
} else {
board.setIcon(new ImageIcon(original));
timer.stop();
// Animation has stopped, make call back...
if (callBack != null) {
callBack.animationDone();
}
}
flashCount++;
}
});
timer.setRepeats(true);
JPanel buttons = new JPanel(new GridLayout(0, 2));
final JButton btnOne = new JButton("#1");
buttons.add(btnOne);
btnOne.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
flashCount = 0;
flashTimes = 1;
flashColor = (int) Math.round(Math.random() * 3);
timer.restart();
btnOne.setEnabled(false);
// Set the call back so we know when the
// animation has stopped...
callBack = new AnimationCallBack() {
@Override
public void animationDone() {
btnOne.setEnabled(true);
}
};
}
});
final JButton btnTwo = new JButton("#2");
buttons.add(btnTwo);
btnTwo.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
flashCount = 0;
flashTimes = 3;
flashColor = (int) Math.round(Math.random() * 3);
timer.restart();
btnTwo.setEnabled(false);
// Set the call back so we know when the
// animation has stopped...
callBack = new AnimationCallBack() {
@Override
public void animationDone() {
btnTwo.setEnabled(true);
}
};
}
});
add(buttons, BorderLayout.SOUTH);
}
protected Image createImage(Color color) {
BufferedImage img = new BufferedImage(400, 400, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = img.createGraphics();
g2d.setColor(color);
g2d.fillRect(0, 0, 400, 400);
return img;
}
@Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
}
public interface AnimationCallBack {
public void animationDone();
}
}