我已编写此代码来更新进度条进度消息。基本上，当我有for（）循环运行的长度进程时，我将其抛入循环中，并使用prog = i和max =数组最大值进行更新。
for(int i = 1; i <= array.length-1; i++){
//Process
setPrg(this.lbl, ths.prg, i, array.length-1, "Doing so process");
}
-
public void setPrg(JLabel lbl, JProgressBar prg, int prog, int max, String msg) {
prg.setMaximum(max);
if (prog <= max) {
prg.setValue(prog);
}
prg.update(prg.getGraphics());
if (prog >= max) {
setMessage(lbl, "");
} else {
setMessage(lbl, msg);
}
}
public void setMessage(JLabel lbl, String msg) {
lbl.setText(msg);
lbl.update(lbl.getGraphics());
}
我使用多个连续的for（）循环执行此操作，每个循环都有描述该过程的唯一消息。
问题是，由于某种原因，标签文本重叠在其自身上。例如，如果我有一个运行此代码的循环：
setPrg(this.lbl, ths.prg, i, array.length-1, "This is process 1");
运行此代码的人：
setPrg(this.lbl, ths.prg, i, array.length-1, "The second process this is");
然后，第二个流程开始后，两条消息中的文本将重叠，而不是“这是流程1”消失。
另一方面，如果我不包括这一行：
lbl.update(lbl.getGraphics());
在循环过程中根本不会显示任何文本，只有最后一个标签文本会在循环后显示。
非常感谢！
这是完整的程序：
package test;
import javax.swing.JLabel;
import javax.swing.JProgressBar;
public class Main extends javax.swing.JFrame {
public Main() {
initComponents();
}
public void setPrg(JLabel lbl, JProgressBar prg, int prog, int max, String msg) {
prg.setMaximum(max);
if (prog <= max) {
prg.setValue(prog);
}
prg.update(prg.getGraphics());
if (prog >= max) {
setMessage(lbl, "");
} else {
setMessage(lbl, msg);
}
}
public void setMessage(JLabel lbl, String msg) {
lbl.setText(msg);
lbl.update(lbl.getGraphics());
}
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jButton1 = new javax.swing.JButton();
jProgressBar1 = new javax.swing.JProgressBar();
jLabel1 = new javax.swing.JLabel();
jTextField1 = new javax.swing.JTextField();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jButton1.setText("Button");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
jLabel1.setText("jLabel1");
jTextField1.setText("jTextField1");
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(246, 246, 246)
.addComponent(jLabel1))
.addGroup(layout.createSequentialGroup()
.addGap(226, 226, 226)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jButton1)))
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jProgressBar1, javax.swing.GroupLayout.PREFERRED_SIZE, 540, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap(108, Short.MAX_VALUE)
.addComponent(jButton1)
.addGap(22, 22, 22)
.addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 31, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18)
.addComponent(jProgressBar1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(40, 40, 40))
);
pack();
}// </editor-fold>
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
for (int i = 1; i <= 10000; i++) {
this.setPrg(jLabel1, jProgressBar1, i, 10000, "Message 1");
}
for (int i = 1; i <= 10000; i++) {
this.setPrg(jLabel1, jProgressBar1, i, 10000, "Second Message");
}
}
public static void main(String args[]) {
//<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(Main.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(Main.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(Main.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(Main.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new Main().setVisible(true);
}
});
}
// Variables declaration - do not modify
public javax.swing.JButton jButton1;
public javax.swing.JLabel jLabel1;
public javax.swing.JProgressBar jProgressBar1;
public javax.swing.JTextField jTextField1;
// End of variables declaration
}
答案 0 :(得分：4)
使用Swing时，您将自动处于多线程环境中。一个是主 - Thread和Swing使用EDT进行UI重绘。
使用 SwingUtilities.invokeLater（）在EventDispatchThread上执行 JProgressBar.setValue（）和 JLabel.setValue（）。这可以确保它们相应地更新。
如何使用 SwingUtilities 。
的示例摘录 final JProgressBar prg = new JProgressBar();
final JLabel lbl = new JLabel();
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
prg.setValue(70);
lbl.setText("Text");
}
});
您将看到，不再需要您对 lbl.update（lbl.getGraphics（））; 的调用。
答案 1 :(得分：2)
您的问题是在Swing事件线程上运行长时间运行的代码以及进行无效的Swing图形调用的经典问题。解决方案是在后台线程中执行长时间运行的代码，例如SwingWorker的doInBackground方法，并注意在Swing事件线程上进行所有Swing调用。
所有这些都在易于查找的教程中得到了很好的解释，包括
例如，编译并运行它：
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.concurrent.ExecutionException;
import javax.swing.*;
@SuppressWarnings("serial")
public class Main4b extends JPanel {
private static final int MAX = 10000;
private static final int PREF_W = 400;
private static final int PREF_H = 200;
private ButtonAction buttonAction = new ButtonAction();
private JButton button = new JButton(buttonAction);
private JTextField jTextField1 = new JTextField("jTextField1", 10);
private JLabel jLabel1 = new JLabel("jLabel1");
private JProgressBar jProgressBar1 = new JProgressBar(0, MAX);
public Main4b() {
jProgressBar1.setStringPainted(true);
setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS));
add(new JPanel() {{add(button);}});
add(new JPanel() {{add(jTextField1);}});
add(new JPanel() {{add(jLabel1);}});
add(jProgressBar1);
setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
}
@Override
public Dimension getPreferredSize() {
Dimension superSz = super.getPreferredSize();
if (isPreferredSizeSet()) {
return superSz;
}
int prefW = Math.max(superSz.width, PREF_W);
int prefH = Math.max(superSz.height, PREF_H);
return new Dimension(prefW, prefH);
}
private class ButtonAction extends AbstractAction {
public ButtonAction() {
super("Button");
}
@Override
public void actionPerformed(ActionEvent e) {
setEnabled(false); // make the button non-pressable
// create background thread worker
MyWorker myWorker = new MyWorker();
// add propertychange listener to it
myWorker.addPropertyChangeListener(new WorkerListener());
// run the worker thread
myWorker.execute();
}
}
// background thread
private static class MyWorker extends SwingWorker<Void, Integer> {
private static final String MY_PROGRESS = "my progress";
private int myProgress = 0;
@Override
protected Void doInBackground() throws Exception {
// all this code is run in a background thread
// do this twice
for (int j = 0; j < 2; j++) {
// iterate from 0 to 10,000
for (int i = 0; i < MAX; i++) {
Thread.sleep(1); // small delay so we can see what we're doing
setMyProgress(i + j * MAX); // send output to listeners
}
}
return null;
}
public int getMyProgress() {
return myProgress;
}
// myProgress is a "bound" field, one that will notify listeners
// if it is changed
public void setMyProgress(int myProgress) {
int oldValue = this.myProgress;
int newValue = myProgress;
this.myProgress = myProgress;
// notify all listeners
firePropertyChange(MY_PROGRESS, oldValue, newValue);
}
}
private class WorkerListener implements PropertyChangeListener {
private String message = "Message %d: %05d";
public WorkerListener() {
jLabel1.setText(String.format(message, 1, 0));
}
@Override
public void propertyChange(PropertyChangeEvent evt) {
// all this code is run on the Swing event thread
// listen for changes to my progress bound field
if (MyWorker.MY_PROGRESS.equals(evt.getPropertyName())) {
int value = (int) evt.getNewValue(); // get value
int newMsgIndex = 1 + value / MAX; // message number
jProgressBar1.setValue(value % MAX); // set value on progress bar
jLabel1.setText(String.format(message, newMsgIndex, value % MAX));
} else if (evt.getNewValue() == SwingWorker.StateValue.DONE) {
// worker is done
jLabel1.setText(""); // reset JLabel
buttonAction.setEnabled(true); // re-enable JButton's Action
MyWorker myWorker = (MyWorker) evt.getSource();
try {
// always call this to catch and handle any exceptions that
// may have been thrown from within the worker
myWorker.get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}
}
private static void createAndShowGui() {
Main4b mainPanel = new Main4b();
JFrame frame = new JFrame("Main");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}