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我正在尝试编写一个 Java 程序，当您单击 JFrame 中的某个元素时，会更改 JLabel 的背景。事件处理方法调用以更改背景的函数在从事件调用时不起作用，但是只要您在独立于任何事件的某处调用该方法，它就会起作用。有谁知道您将如何更改 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();
}
  • 注意：上面的代码仅用于显示我的问题。它实际上不是我的代码的一部分。我没有发布代码，因为我正在和一个朋友一起开发这个程序，他不想发布代码，即使它只是其中的一小部分，无法做任何有价值的事情。

编辑：根据所有试图帮助我的人的请求，我已将 NetBeans 项目工作区以 zip 文件的形式上传到 FileDropper，您可以在此处下载。您会注意到，当我从主类调用该方法时，它确实会闪烁另一个图像并根据需要返回到当前图像，但是当您释放鼠标单击“播放”时，它不会调用它，即使它应该。随意尝试代码。

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，所以这里是：

西蒙.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();
    }
}

西蒙GUI.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);
    }
}

*其中一些代码是使用 NetBeans 的 Swing GUI 设计器插件自动生成的。

4

2 回答 2

2

  1. JLabel默认是透明的，要改setOpaque()

  2. 我不知道什么MouseReleaseEvent是方法，不要重定向 Swing 事件（在某些情况下是可能的并且需要，但对于 newbee 不是），

  3. 在MouseListener中实现的标准事件是mousePressed, mouseReleased, mouseEntered, mouseExited, mouseClicked

  4. 阅读 Oracle 教程如何编写鼠标侦听器以获取工作示例和各种不同的事件类型

于 2013-08-16T06:08:08.650 回答
1

根据示例代码，至少有两件事我可以担心

  1. null布局的使用。每个系统都是独一无二的，有自己的字体、屏幕分辨率和 DPI 属性。为了克服这个问题，并更容易编写复杂的用户界面，不仅可以在不同的计算机上工作，而且可以在不同的操作系统上工作，开发了布局管理 API。强烈建议您查看在容器内布局组件
  2. Thread.sleep在 Event Dispatching Thread 内使用。

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 Event Dispatching Thread 的上下文中。任何阻塞此线程的操作都会阻止它处理绘画请求等。

这意味着当您执行时Thread.sleep，您将阻止 EDT 更新 UI，直到您所在的方法退出...

我能为您想到的最简单的解决方案是使用javax.swing.Timer. 下面是一个简单的例子来演示这个想法。

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，我会改变你的playBackPattern方法来启动一个javax.swing.Timer，如果你想要的话，可以调用你的flashColor方法，例如......

有关更多详细信息，请参阅Swing 中的并发。

更新了“回叫”功能

这提供了一个提供回调功能的非常基本的示例，这样当动画停止时，它会对指定的对象进行回调。

就个人而言，我宁愿做的稍微不同，但它过于复杂了这个例子......

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();
    }
}
于 2013-08-17T22:22:38.827 回答