一个可视指示符显示收集成功完成还是失败(当收集完成且没有出现错误时，进度条为绿色；而收集失败时则为红色)。
A visual indicator shows if the collection has ended successfully or failed (the progress bar is green when collection is completed with no errors, or red when it fails).
这意味着如果没有进度条或是其他指示器，用户会觉得你的程序跑得很慢。
This means that without progress bars or some other indicators your application will feel slower to your users.
在默认情况下，除了进度条外，没有其他关于进度的图形指示。
By default, there is no graphical indication of progress besides the bar.
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