将默认光标更改为繁忙光标无法按预期工作

经过多次尝试JProgressBar按照预期的工作，我终于成功地实现了我的目标。我曾经用过@疯狂程序员's advice并使用了SwingWorker最终让程序按我想要的方式工作。

Now, I want the cursor to change into when my JProgressBar goes from 0% to 100%. I've googled and found out that

setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));

是执行此操作的代码。我已经尝试过，但它没有按预期工作。

相关代码段：

JProgressBar progress;
JButton button;     
JDialog dialog;      //Fields of my GUI class

progress=new JProgressBar(JProgressBar.HORIZONTAL,0,100);
button=new JButton("Done");
dialog=new JDialog();             //Done from methods

progress.setValue(0);
progress.setStringPainted(true);
progress.setBorderPainted(true);  //Also done from methods

button.addActionListener(this);   //Also done from methods

dialog.setLayout(new FlowLayout(FlowLayout.CENTER));
dialog.setTitle("Please wait...");
dialog.setBounds(475,150,250,100);
dialog.setModal(true);            //Also done from methods

dialog.add(new JLabel("Loading..."));
dialog.add(progress);             //Also done from methods

这是actionPerformed method:

public void actionPerformed(ActionEvent e)
{
    setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));

    Task task=new Task();
    task.addPropertyChangeListener(this);
    task.execute();
    dialog.setVisible(true);
}

The propertyChange method:

public void propertyChange(PropertyChangeEvent evt) {
    if("progress" == evt.getPropertyName()){
        int progressnum = (Integer) evt.getNewValue();
        progress.setValue(progressnum);
    }
}

和嵌套类Task:

   class Task extends SwingWorker<Void, Void> {
        /*
         * Main task. Executed in background thread.
         */
        @Override
        public Void doInBackground() {
            int progressnum = 0;
            setProgress(0);

            while (progressnum < 100) {
                try {
                    Thread.sleep(10);
                } catch (InterruptedException ex) {
                    System.err.println("An error occured:"+ex);
                    ex.printStackTrace();
                }

                progressnum ++;
                setProgress(Math.min(progressnum, 100));
            }
            return null;
        }

        /*
         * Executed in event dispatching thread
         */
        @Override
        public void done() {
            //setCursor(null); //turn off the wait cursor
            setCursor(Cursor.getDefaultCursor()); //Is this one or the one above it right?
            dialog.dispose();
            progress.setValue(progress.getMinimum());
        }
    }

When I press button, the JDialog with the JProgressBar appears and the JProgressBar goes from 0% to 100%. During this time, the cursor needs to be changed into (busy cursor) and when the JProgressBar reaches 100%, the normal cursor( ) needs to be restored.

问题是，当我按button，光标瞬间变为繁忙光标，然后又变回原始光标。我希望光标一直处于忙碌状态，直到 JProgressBar 达到 100%。

我添加了将光标转换为忙碌光标的代码actionPerformed方法并恢复正常光标done嵌套类的方法Task。请注意，我还包含了必要的软件包。

• 是什么导致了这个问题？
• 我如何解决它？

• 我应该使用

  setCursor(null);
  

  or

  setCursor(Cursor.getDefaultCursor());
  

  恢复光标？

你打电话时setCursor() on the JFrame，它只对框架有效，对对话框无效。同样，当你打电话时setCursor() on the JDialog，它只对对话框有效，对框架无效。问题在于：您没有为对话框设置光标，对吧？

我不确定是否setCursor(null)比安全setCursor(Cursor.getDefaultCursor()). :p