Unknown error: java.lang.NullPointerException.

编译工程的时候遇到RT错误，诡异的是之前都是好的，我就改了改makefile和lib工程的文件

最后找到了方法

I was getting the error when I created a new Android project from source in eclipse and it stumped me for a bit until I took a look at the .project file.  For some reason even after I updated the library links, the old links were not removed.  This is what was causing the Unknown error: java.lang.NullPointerException.

This should cause the workspace to be re-built and the .project file will get corrected.To fix it close Eclipse and edit your .project file and remove the section and ALL of the links inside. Then go back into eclipse re-setup the links and do a clean (Project->Clean in the menu) on the affected project.

Happy Developing!

把 .project 下面的 标签删掉，clean再build就对了