java - 当鼠标进入按钮时 jLabel 幻灯片显示

Question

我无法让它工作:

public void ru() throws InterruptedException {
    jLabel3.setIcon(new javax.swing.ImageIcon(getClass().getResource("/adv/room.jpg")));
    setVisible(true);
    Thread.sleep(400);
    jLabel3.setIcon(new javax.swing.ImageIcon(getClass().getResource("/adv/ROOMS.jpg")));
    setVisible(true);
    Thread.sleep(400);
    jLabel3.setIcon(new javax.swing.ImageIcon(getClass().getResource("/adv/background.jpg")));
    setVisible(true);
}

private void BtnRoomsMouseEntered(java.awt.event.MouseEvent evt) {
    try {
        ru();
    } catch (InterruptedException ex) {
    }
}               

有什么解决办法吗？我希望 jLabel 在鼠标进入某个按钮时显示幻灯片，并且只要鼠标仍在按钮中就保持这种状态。如果鼠标恰好退出按钮，jlabel 将返回到 null 状态。 (不再有任何东西。) 这可能吗？请帮忙。我也尝试过使用 for 语句，但效果不佳。顺便说一句，我正在使用 netbeans。

Answer 1

首先您需要实现一个javax.swing.Timer。尝试调用 Thread.sleep() 会阻塞 Event Dispatch Thread 。请参阅How to use Swing Timers 。这是基本结构

Timer(int delay, ActionListener listener) 

其中delay是您想要延迟的时间(以毫秒为单位)，listener将监听TimerActionEvent每延迟毫秒触发一次。

所以你想要这样的东西

public class MyFrame extends javax.swing.JFrame {

   private Timer timer = null;
   ImageIcon[] icons = new ImageIcon[3];
   int index = -1;

   public MyFrame() {
       initComponents();
       icons[0] = new ImageIcon(...);
       icons[1] = new ImageIcon(...);
       icons[2] = new ImageIcon(...);

       timer = new Timer(2000, new ActionListener(){
           public void actionPerformed(ActionEvent e) {
               if (index + 1 > 2) {
                   index = 0;
                   jLabel3.setIcon(icons[index]);
               } else {
                   index++;
                   jLabel3.setIcon(icons[index]);
               }
           }
       });
   }
}

对于您的按钮，您需要使用 mouseEntered 和 mouseExited，然后您只需调用 timer.start() 或 timer.stop()

private void jButton1MouseExited(MouseEvent e) {
    timer.stop();
}

private void jButton1MouseEntered(MouseEvent e) {
    timer.start();
}

如果您不知道如何添加MouseListener，只需右键单击设计 View 中的按钮，然后选择Event -> Mouse -> mouseEntered。对 mouseExited 执行相同的操作。您应该会看到自动生成的上述方法。

<小时/>

更新

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.GroupLayout;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.Timer;
import javax.swing.WindowConstants;

public class ImageViewer extends javax.swing.JFrame {

    private Timer timer = null;
    ImageIcon[] icons = new ImageIcon[5];
    int index = -1;

    public ImageViewer() {
        initComponents();
        try {

            icons[0] = new ImageIcon(new URL("http://www.iconsdb.com/icons/preview/orange/stackoverflow-4-xxl.png"));
            icons[1] = new ImageIcon(new URL("http://www.iconsdb.com/icons/preview/caribbean-blue/stackoverflow-4-xxl.png"));
            icons[2] = new ImageIcon(new URL("http://www.iconsdb.com/icons/preview/royal-blue/stackoverflow-4-xxl.png"));
            icons[3] = new ImageIcon(new URL("http://www.iconsdb.com/icons/preview/moth-green/stackoverflow-4-xxl.png"));
            icons[4] = new ImageIcon(new URL("http://www.iconsdb.com/icons/preview/soylent-red/stackoverflow-4-xxl.png"));
        } catch (MalformedURLException ex) {
            Logger.getLogger(ImageViewer.class.getName()).log(Level.SEVERE, null, ex);
        }

        timer = new Timer(1000, new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (index + 1 > 4) {
                    index = 0;
                    jLabel1.setIcon(icons[index]);
                } else {
                    index++;
                    jLabel1.setIcon(icons[index]);
                }
            }
        });
    }

    /**
     * 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() {

        jButton1 = new JButton();
        jLabel1 = new JLabel();

        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        jButton1.setText("jButton1");
        jButton1.addMouseListener(new MouseAdapter() {
            public void mouseEntered(MouseEvent evt) {
                jButton1MouseEntered(evt);
            }
            public void mouseExited(MouseEvent evt) {
                jButton1MouseExited(evt);
            }
        });

        GroupLayout layout = new GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGroup(GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(jButton1)
                .addGap(127, 127, 127))
            .addGroup(layout.createSequentialGroup()
                .addGap(27, 27, 27)
                .addComponent(jLabel1, GroupLayout.PREFERRED_SIZE, 285, GroupLayout.PREFERRED_SIZE)
                .addContainerGap(29, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGroup(GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addGap(22, 22, 22)
                .addComponent(jLabel1, GroupLayout.DEFAULT_SIZE, 321, Short.MAX_VALUE)
                .addGap(18, 18, 18)
                .addComponent(jButton1)
                .addGap(16, 16, 16))
        );

        pack();
    }// </editor-fold>                        

    private void jButton1MouseEntered(MouseEvent evt) {                                      
        timer.start();
    }                                     

    private void jButton1MouseExited(MouseEvent evt) {                                     
        timer.stop();
    }                                    

    /**
     * @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(ImageViewer.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(ImageViewer.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(ImageViewer.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(ImageViewer.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 ImageViewer().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private JButton jButton1;
    private JLabel jLabel1;
    // End of variables declaration                   
}