我正在使用JProgressBar来显示进度。但是，如何将progressBar显示为从0加载到100？我从互联网及其工作中获得了代码，但progressBar没有加载。
码
progressFrame = new JFrame(); // frame to display progress bar
progressBar = new JProgressBar(0,100);
progressBar.setValue(0);
progressBar.setStringPainted(true);
progressFrame.add(progressBar);
new SwingWorker<Void,Void>()
{
protected Void doInBackground() throws SQLException, ClassNotFoundException
{
Class.forName("oracle.jdbc.driver.OracleDriver");
progressBar.setValue(0);
frame.setEnabled(false); // frame = main frame
//tableclass creates a JTable with data from database
tableclass = new TheDatabaseTable(deptName);//it takes time to create
progressBar.setValue(50);
frame.getContentPane().removeAll();
frame.setContentPane(tableclass);
frame.validate();
frame.repaint();
progressBar.setValue(100);
//progressFrame.dispose();
return null;
};
protected void done()
{
//progressFrame.setVisible(false);
frame.setVisible(true);
progressFrame.dispose();
frame.setEnabled(true);
}
}.execute();
如果有人编辑上述代码，我将不胜感激。谢谢。
答案 0 :(得分：10)
要从网上爱代码......哦......
你所拥有的代码违反了Swing的单线程规则，因此是一个不好的例子。
SwingWorker有很多选项。您可以publish进度并使用process方法更新进度条，或者您可以使用PropertyChangeListener并监控通过调用setProgress方法创建的进度更改事件SwingWorker
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.SwingWorker;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;
public class SwingWorkerProgress {
public static void main(String[] args) {
new SwingWorkerProgress();
}
public SwingWorkerProgress() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JProgressBar pbProgress;
private JButton start;
public TestPane() {
setBorder(new EmptyBorder(10, 10, 10, 10));
pbProgress = new JProgressBar();
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.insets = new Insets(4, 4, 4, 4);
gbc.gridx = 0;
gbc.gridy = 0;
add(pbProgress, gbc);
start = new JButton("Start");
gbc.gridy++;
add(start, gbc);
start.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
start.setEnabled(false);
ProgressWorker pw = new ProgressWorker();
pw.addPropertyChangeListener(new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent evt) {
String name = evt.getPropertyName();
if (name.equals("progress")) {
int progress = (int) evt.getNewValue();
pbProgress.setValue(progress);
repaint();
} else if (name.equals("state")) {
SwingWorker.StateValue state = (SwingWorker.StateValue) evt.getNewValue();
switch (state) {
case DONE:
start.setEnabled(true);
break;
}
}
}
});
pw.execute();
}
});
}
}
public class ProgressWorker extends SwingWorker<Object, Object> {
@Override
protected Object doInBackground() throws Exception {
int i = 0;
int max = 2000;
while (i < max) {
i += 10;
int progress = Math.round(((float)i / (float)max) * 100f);
setProgress(progress);
try {
Thread.sleep(25);
} catch (Exception e) {
e.printStackTrace();
}
}
return null;
}
}
}
答案 1 :(得分：5)
你必须使用线程。设计一个实现Runnable接口的类，它将更新这样的值。
class ProgressBarUpdator implements java.lang.Runnable {
/**
* Progress bar that shows the current status
*/
private javax.swing.JProgressBar jpb = null;
/**
* Progress bar value
*/
private java.lang.Integer value = null;
/**
* Constructor
* @param jpb The progress bar this has to update
*/
public ProgressBarUpdator(javax.swing.JProgressBar jpb) {
this.jpb = jpb;
jpb.setMaximum(100);
}
/**
* Sets the value to the progress bar
* @param value Value to set
*/
public void setValue(java.lang.Integer value) {
this.value = value;
}
/**
* Action of the thread will be executed here. The value of the progress bar will be set here.
*/
public void run() {
do {
if (value != null) {
jpb.setValue((int)java.lang.Math.round(java.lang.Math.floor(value.intValue() * 100 / maximum)));
}
try {
java.lang.Thread.sleep(100L);
} catch (java.lang.InterruptedException ex) {
ex.printStackTrace();
}
} while (value == null || value.intValue() < jpb.getMaximum());
}
}
并在您的框架类中使用progressBar和新的类
ProgressBarUpdator ju = new ProgressBarUpdator(progressBar);
new java.lang.Thread(ju).start();
每当您想要更改值时，只需使用语句
ju.setValue([Value to set]);
答案 2 :(得分：-1)
import java.awt.GridBagLayout;
import javax.swing.JFrame;
import javax.swing.JProgressBar;
public class ProgressBar {
/**
* JProgressBar
*
* @throws InterruptedException
*/
public static void main(String[] args) throws InterruptedException {
JFrame frame = new JFrame("New Window");
frame.setSize(600, 400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setLayout(new GridBagLayout());
frame.setVisible(true);
//JLabel textLoad = new JLabel();
//textLoad.setText("Loading ....");
JProgressBar progressBar = new JProgressBar();
progressBar.setMinimum(0);
progressBar.setMaximum(100);
progressBar.setStringPainted(true);
progressBar.setIndeterminate(true);
frame.add(progressBar);
for (int i = progressBar.getMinimum(); i <= progressBar.getMaximum(); i++) {
Thread.sleep(500);
progressBar.setValue(i);
}
textLoad.setText("Done !");
}
}
答案 3 :(得分：-2)
/*
By
Dr. Amit Kumar Kapoor
Assistant Professor, Maharaja Agrasen Institute of Management & Technology, Jagadhri
E-mail ID: akbrightfuture@gmail.com
*/
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
class progressbardemo extends JFrame implements ActionListener
{
JProgressBar pb;
JButton b1;
progressbardemo()
{
super("Progressbar");
setLayout(null);
b1=new JButton("Click");
b1.setBackground(Color.yellow);
pb=new JProgressBar(1,100);
pb.setValue(0);
pb.setStringPainted(true);
pb.setForeground(Color.red);
pb.setBackground(Color.white);
b1.setBounds(20,20,80,25);pb.setBounds(110,20,200,25);
pb.setVisible(false);
add(b1);
add(pb);
b1.addActionListener(this);
setResizable(false);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent e)
{
int i=0;
if(e.getSource()==b1)
{
pb.setVisible(true);
try
{
while(i<=100)
{
Thread.sleep(50);
pb.paintImmediately(0, 0, 200, 25);
pb.setValue(i);
i++;
}
}
catch(Exception e1)
{
System.out.print("Caughted exception is ="+e1);
}
}
}
public static void main(String arg[])
{
progressbardemo m=new progressbardemo();
m.setSize(330,100);
m.setVisible(true);
Dimension dimension = Toolkit.getDefaultToolkit().getScreenSize();
int x = (int) ((dimension.getWidth() - m.getWidth()) / 2);
int y = (int) ((dimension.getHeight() - m.getHeight()) / 2);
m.setLocation(x, y);
}
}