http://forums.netbeans.org/topic39013.html
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I have a package with just one class. I had to rename that class, so I went ahead and in the Projects window, right clicked the class and selected Rename from Refactor, and in the Rename class window I typed in the new name. NetBeans renamed the file and also the class in the file. It did a great job on that one, but after that it threw a red squegly line below the class name. And when I hover over that line, it says Duplicate class: pkgname.ClassName.
I tried but couldn't figure what the problem is?
I ran into the same problem. I was able to fix the problem by shutting down netbeans and deleting the cache directory in c:\documents and settings\<user>\.netbeans\7.0\var. When i started netbeans everything was back to normal.
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Win7中的实际目录是C:\Users\admin\AppData\Local\NetBeans\Cache