Swing进度条通过Worker更新到EventDispatch线程 [英] Swing Progress Bar updates via Worker to EventDispatch thread

问题描述

我有一个 JAVA6 GUI处理数据导入到我们的数据库。我已经实现了一个有效的JProgressBar。我知道对GUI的更改必须通过事件派发线程来完成 - 我认为我没做（正确/完全）。

背景工作线程UploadWorker是通过传入在主程序中创建的JProgressBar构建的，并在完成后直接设置更改进度条的值：

  //构造时，将其设置为主程序的JProgressBar。 
 JProgressBar进度; 
 
 
 
 protected Void doInBackground（）抛出异常{
 write（<！ -  Import from+ getCurrentTime（）+ - > \\\
）; 
 boolean chunked = false; 
 switch（importMethod）{
 
 //做一些导入
 
} 
 
写（<！ - 导入尝试已完成at+ getCurrentTime（）+ - > \ n）; 
 
 //这里对GUI的更改是
 progress.setMaximum（0）; 
 progress.setIndeterminate（false）; 
 progress.setString（完成工作）; 
返回null; 
} 
  

这样可以正常工作，但有时候（并不总是）会让我看到几个NPE std out，用户抱怨：

 线程中的异常AWT-EventQueue-0java.lang.NullPointerException 
在javax.swing.plaf.basic.BasicProgressBarUI.updateSizes（未知来源）
 ...等... 
  

无论如何，我相信我需要做些什么才能在正确的线程上执行这些更新，对吗？如何？

解决方案

你可以创建一个新的Runnable来执行GUI更新并使用SwingUtilities.invokeLater在GUI线程中调用它/ p>

I have a JAVA6 GUI handling data import to our database. I have implemented a working JProgressBar. I understand that changes made to the GUI must be done via the event dispatch thread--which I do not think I am doing (properly/at all).

the background Worker thread, UploadWorker, is constructed by passing in the a JProgressBar created in the main program, and sets changes the value of the progress bar directly once it is finished:

// when constructed, this gets set to the main program's JProgressBar.
JProgressBar progress; 



protected Void doInBackground() throws Exception {
    write("<!-- Import starting at " + getCurrentTime() + " -->\n");
    boolean chunked = false;
    switch (importMethod) {

            //do some importing

    }

    write("<!-- Import attempt completed at " + getCurrentTime() + "-->\n");

    //here changes to the GUI are made
    progress.setMaximum(0);
    progress.setIndeterminate(false);
    progress.setString("Finished Working");
    return null;
}

This works fine, but sometimes(not always) throws me several NPE's in the std out, and users are complaining:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.plaf.basic.BasicProgressBarUI.updateSizes(Unknown Source)
...etc...

Anyway, I believe there is something I need to do to get these updates executed on the proper thread, correct? How?

解决方案

You can just create a new Runnable that performs GUI updates and invoke it in a GUI thread using SwingUtilities.invokeLater

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