[英]Java JList Model addElement() breaks visual representation of the list
只是有奇怪的行为,然后将元素添加到JList模型。 调用addElement()方法时,列表变为空白,而是添加巨大的空元素,或者将新元素向下移动几行。 对该方法的另一次调用将问题放回原处,并将其放到问题发生之前和之后的所有元素,包括通过“不稳定”调用添加的项目。 首先,它似乎是绘画问题,只是repaint调用无济于事,仅添加新元素即可解决问题。
然后发生问题,然后添加部分元素,涉及不同启动的相同索引。 从来没有见过它很快就失败了。
package r;
import java.io.IOException;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import javax.swing.DefaultListModel;
import javax.swing.JOptionPane;
public class R extends javax.swing.JFrame {
ServerSocket serverport;
/**
* Creates new form R
*/
public R() {
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() {
scrollDebug = new javax.swing.JScrollPane();
debugList = new javax.swing.JList();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setTitle("Debug");
addWindowListener(new java.awt.event.WindowAdapter() {
public void windowOpened(java.awt.event.WindowEvent evt) {
formWindowOpened(evt);
}
});
scrollDebug.setAutoscrolls(true);
debugList.setSelectionMode(javax.swing.ListSelectionModel.SINGLE_SELECTION);
scrollDebug.setViewportView(debugList);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(scrollDebug, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 682, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(scrollDebug, javax.swing.GroupLayout.DEFAULT_SIZE, 383, Short.MAX_VALUE)
);
pack();
setLocationRelativeTo(null);
}// </editor-fold>
private void formWindowOpened(java.awt.event.WindowEvent evt) {
new Thread() {
@Override
public void run() {
try {
serverport = new ServerSocket(33002, 0, InetAddress.getLoopbackAddress());
debugList.setModel(new DefaultListModel());
while (R.this.isVisible()) {
new ClientConnection(serverport.accept()).start();
}
} catch (IOException ex) {
JOptionPane.showMessageDialog(null, "Error opening server port", "Debug", JOptionPane.ERROR_MESSAGE);
}
}
}.start();
}
/**
* @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(R.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(R.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(R.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(R.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 R().setVisible(true);
}
});
}
class ClientConnection extends Thread {
Socket connection;
public ClientConnection(Socket connection){
this.connection=connection;
}
@Override
public void run() {
try {
connection.getOutputStream().write(String.format("debug>").getBytes());
connection.getOutputStream().flush();
String response = "";
do {
response += (char) connection.getInputStream().read();
} while (!response.endsWith(System.lineSeparator()));
response = response.replace(System.lineSeparator(), "");
((DefaultListModel) debugList.getModel()).addElement(response);
if (((DefaultListModel) debugList.getModel()).getSize() > 0) {
//debugList.ensureIndexIsVisible(((DefaultListModel) debugList.getModel()).getSize() - 1);
debugList.setSelectedIndex(((DefaultListModel) debugList.getModel()).getSize() - 1);
scrollDebug.getVerticalScrollBar().setValue(scrollDebug.getVerticalScrollBar().getMaximum());
}
connection.close();
} catch (IOException ex) {
JOptionPane.showMessageDialog(null, "Error receiving connection", "Debug", JOptionPane.ERROR_MESSAGE);
}
}
}
// Variables declaration - do not modify
private javax.swing.JList debugList;
private javax.swing.JScrollPane scrollDebug;
// End of variables declaration
}
现在添加了完整的示例代码。 对造成的不便表示歉意!
这是框架的内部类,用于创建新线程来接收数据并将字符串添加到JList。
Swing组件需要在事件分发线程上进行更新,因此您不能直接在线程中更新该组件。
因此,您可以将更新模型的代码包装在SwingUtilities.invokeLater(...)
或者,可以使用SwingWorker
并在结果可用时“发布”而不是使用单独的线程。
阅读Swing 并发教程中的这一节,以获取有关这些概念和工作示例的更多信息。
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