安卓手机软件开发需要什么知识，在什么平台上开发？

 问题是UI只在run（event）循环转动时定期更新。 一个for()循环，我假设在主线程上运行，将阻止运行循环直到完成。 这不仅意味着进度条不会更新（或者更确切地说，最后会直接跳到100％），但是您可能会在一段时间内冻结UI。 （我假设，因为你正在显示一个进度条，这可能需要一段时间。） 
 
 对于任何冗长的操作，您想要做的是在单独的队列/线程上完成工作，并定期调用主线程上的UI更新。 例如，您可能会尝试类似（ 警告：在浏览器中键入 ）： 
 
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0);
dispatch_async(queue, ^{
    int j = 1000;
    for (int i=0; i<j; i++) {
        // Do your presumably useful work, not just looping for fun :-)
        dispatch_async(dispatch_get_main_queue(), ^{
            // UI updates always come from the main queue!
            calculatingProgressBar.progress = (i/j);
        });
    }
});
 
 此示例使用GCD（ Grand Central Dispatch ）。 你可以看到更高级别的结构，比如NSOperationQueue ，但基本思想保持不变。 
 
 如果您不熟悉并发（多线程）编程，那么您将获得适度的学习曲线以加快速度。 我建议从“ 并发编程指南”开始 。 

The problem is that the UI is only updated periodically as the run (event) loop turns. A for() loop, which I am assuming runs on the main thread, is going to block the run loop until finished. Not only does this mean the progress bar won't be updated (or, rather, will jump right to 100% at the end), but that you are potentially going to freeze the UI for some time. (I assume, since you are showing a progress bar, that this could take a while.)
 
What you want to do, for any lengthy operation, is to have the work done on a separate queue/thread, and call out the update the UI on the main thread periodically. For example, you might try something like (warning: typed in browser):
 
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0);
dispatch_async(queue, ^{
    int j = 1000;
    for (int i=0; i<j; i++) {
        // Do your presumably useful work, not just looping for fun :-)
        dispatch_async(dispatch_get_main_queue(), ^{
            // UI updates always come from the main queue!
            calculatingProgressBar.progress = (i/j);
        });
    }
});
 
This example uses GCD (Grand Central Dispatch). There are higher level constructs you can also look at, like NSOperationQueue, but the basic idea remains the same.
 
If you are unfamiliar with concurrent (multithreaded) programming, you are going to have a modest learning curve to get up to speed. I suggest starting with the Concurrency Programming Guide.