你能帮我编码一下吗?它是一个计时器，运行一个特定的任务，但它不会停止!我正在使用java.swing.Timer和WebLookAndFeel(你会注意到NotificationManager:它属于WebLaF)。我试着调用自身内部的<timer>.stop();，但它说它没有实例化。我还尝试过添加<timer>.setRepeats(false)，这导致了NPE。<timer>为每个唯一定时器。
没有计时器的编码工作得很好，但最近添加到应用程序中需要使用计时器。
我在编程中使用的大部分东西都是自学的，所以我不太擅长调试计时器。请耐心听我说。
我的代码:Timer updateEB;
try {
updateEB = new Timer(2500, new ActionListener()
@Override
public void actionPerformed(ActionEvent evt) {
System.out.println("Update process started");
try {
// <editor-fold defaultstate="collapsed" desc="Get first message via SQL query">
try {
// Initiate SQL connection and execute query
String sql = "Select * from APP.EBULLETINS ORDER BY msgid DESC FETCH FIRST 2 ROWS ONLY";
Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
Class.forName("org.apache.derby.jdbc.ClientDriver");
Connection con = (Connection) DriverManager.getConnection("jdbc:derby:C:\Program Files\AmalgaIMS\AIMSDB", "xxxxxxx", "xxxxxxxx");
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery(sql);
// Get message details
if (rs.next()) {
eBul1_Title = rs.getString("Title");
eBul1_Msg = rs.getString("Content");
eBul1_Type = rs.getString("MSGTYPE");
}
// Set message fields
eBul1T.setText(eBul1_Title);
eBul1M.setText(eBul1_Msg);
// Debugging purposes
System.out.println("Setting Icons...");
System.out.print("1. ");
// <editor-fold defaultstate="collapsed" desc="Set Message 1 Icon">
if (eBul1_Type.equals("INFORMATION")) {
TypeImage1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/main/MainMenu/Information.png")));
System.out.println("Info");
} else if (eBul1_Type.equals("ANNOUNCEMENT")) {
TypeImage1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/main/MainMenu/announcement.png")));
System.out.println("Announce");
} else if (eBul1_Type.equals("WARNING")) {
TypeImage1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/main/MainMenu/Warning.png")));
System.out.println("Warning");
} else {
TypeImage1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/main/MainMenu/misc 16x16.png")));
System.out.println("Other");
}
// </editor-fold>
} catch (Exception eB1Exc) {
JOptionPane.showMessageDialog(null, eB1Exc);
}
// </editor-fold>
// <editor-fold defaultstate="collapsed" desc="Get second message via SQL query">
try {
// Initiate SQL connection and execute query
String sql = "Select * from app.EBULLETINS ORDER BY msgid DESC FETCH FIRST 2 ROWS ONLY";
Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
Class.forName("org.apache.derby.jdbc.ClientDriver");
Connection con = (Connection) DriverManager.getConnection("jdbc:derby:C:\Program Files\AmalgaIMS\AIMSDB", "xxxxxxxx", "xxxxxxxxx");
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery(sql);
// Get message details
while (rs.next()) {
eBul2_Title = rs.getString("Title");
eBul2_Msg = rs.getString("Content");
eBul2_Type = rs.getString("MSGTYPE");
}
// Debugging purposes
System.out.print("2. ");
// Set message fields
eBul2T.setText(eBul2_Title);
eBul2M.setText(eBul2_Msg);
// <editor-fold defaultstate="collapsed" desc="Set Message 2 Icon">
if (eBul2_Type.equals("INFORMATION")) {
TypeImage2.setIcon(new javax.swing.ImageIcon(getClass().getResource("/main/MainMenu/Information.png")));
System.out.println("Info");
} else if (eBul2_Type.equals("ANNOUNCEMENT")) {
TypeImage2.setIcon(new javax.swing.ImageIcon(getClass().getResource("/main/MainMenu/announcement.png")));
System.out.println("Announce");
} else if (eBul2_Type.equals("WARNING")) {
TypeImage2.setIcon(new javax.swing.ImageIcon(getClass().getResource("/main/MainMenu/Warning.png")));
System.out.println("Warning");
} else {
TypeImage2.setIcon(new javax.swing.ImageIcon(getClass().getResource("/main/MainMenu/misc 16x16.png")));
System.out.println("Other");
}
// </editor-fold>
} catch (Exception eB2Exc) {
eB2Exc.printStackTrace();
}
// </editor-fold>
//<editor-fold defaultstate="collapsed" desc="Update Successful">
//<editor-fold defaultstate="collapsed" desc="Set eBulletin Notification Sound">
try {
// Open an audio input stream.
URL url = this.getClass().getResource("/Resources/Sounds/Notifications/NotifB.wav");
AudioInputStream audioIn = AudioSystem.getAudioInputStream(url);
// Get a sound clip resource.
Clip clip = AudioSystem.getClip();
// Open audio clip from the audio input stream.
clip.open(audioIn);
clip.start();
} catch (UnsupportedAudioFileException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (LineUnavailableException e) {
e.printStackTrace();
}
//</editor-fold>
NotificationManager.showNotification("eBulletins updated!", NotificationIcon.mail.getIcon());
Timer hideNotifs;
try {
hideNotifs = new Timer(3000, new ActionListener() {
@Override
public void actionPerformed(ActionEvent evt) {
NotificationManager.hideAllNotifications();
}
});
hideNotifs.start();
} catch (Exception e) {
e.printStackTrace();
}
} catch (Exception exc) {
exc.printStackTrace();
}
//</editor-fold>
//<editor-fold defaultstate="collapsed" desc="Set Refresh Icon">
try {
lbleBulUpdate.setIcon(new javax.swing.ImageIcon(getClass().getResource("/Resources/refresh 16x16.png")));
} catch (Exception e) {
System.out.println(e);
}
//</editor-fold>
lblEBulStatus.setForeground(new java.awt.Color(51, 255, 0));
lblEBulStatus.setText("ACTIVE");
}
});
updateEB.start();
} catch (Exception e) {
}
您在事件调度线程(或EDT)上进行了大量长时间运行的调用，这将使其无能为力。相反，在后台线程中处理数据库代码和任何其他长时间运行的代码，比如SwingWorker中可用的代码。
说句题外话，这个空catch块让我很害怕:
} catch (Exception e) {
}
注意，如果你想让Timer只运行一次，那么你可以在actionPerformed方法中通过:
((Timer) evt.getSource()).stop();
你甚至可以把它作为actionPerformed方法的第一行