改变ProgressBar的可见性会导致关闭(Changing visibility of ProgressBar causes force close)

 我有一个包含WebView的布局，以及以它为中心的ProgressBar。 进度条需要显示并且保存为程序（当网页内容加载时）。 但是，将ProgressBar设置为使用loading.setVisibility(View.VISIBLE);可见loading.setVisibility(View.VISIBLE); ，导致一个力量关闭。 如果ProgressBar默认是可见的，那么它工作正常。 如果需要，我会粘贴所有适当的代码，但我怀疑我正在做一些根本性的错误。 
 
 （应该有强制关闭标记，但它既不强制关闭也不存在，我无法创建它。） 
 
 好的，代码。 setVisibility简单地说就是： 
 
  public void nowLoading() {
        loading.setVisibility(View.VISIBLE);
    }
 
 nowLoading被称为...通过JavaScript，与WebView上的addJavascriptInterface。 啊...我想象WevView是在一个不同的线程。 我如何解决这个问题？ 

I have a layout containing a WebView, and a ProgressBar centred on top of it. The progress bar needs to be shown and hid programatticaly (as web content loads). However, setting the ProgressBar to be visible using loading.setVisibility(View.VISIBLE);, causes a force close. If the ProgressBar is visible by default it works fine. I will paste all appropriate code if needed, but I suspect I'm doing something fundamentally and simply wrong.
 
(should have force-close tag but neither it nor forceclose exists and I can't create it.)
 
Okay, code. The setVisibility is simply:
 
  public void nowLoading() {
        loading.setVisibility(View.VISIBLE);
    }
 
nowLoading is called... via javascript, with addJavascriptInterface on the WebView. Ahh... I imagine the WevView is in a different Thread. How do I solve that?

原文：https://stackoverflow.com/questions/6084454