导入Android工程提示The project was not built since

解决方案1：

错误提示:The project was not built since its build path is incomplete. Cannot find the class file for java.lang.Object. Fix the build path then try building this project
The type java.lang.Object cannot be resolved. It is indirectly referenced from required .class files

今天在eclipse3.2+myeclipse5.1+tomcat5.5重新部署时出了这问题.搞了很久才找到原因.解决办法写出来分享:

出现以上错误的原因是居然是装jdk5时了多装了个jre。本来Eclipse在建立项目时，会自动参照你的jre路径，但多个版本就没办法加载了。
解决办法：
1. 进入window \ preferences \ java \ Installed JREs
1)按Add
2)输入JRE Name, 例JDK 1.5.0.09
3)JRE home directory, 选择安装的路径
4)按OK
2. 进入Project \ properties \ Java Bulid Path
1)Add library
2)选JRE System Library后按Next
3)选workplace default JRE后按 finish...

解决方案2：

部分网友下载的Android工程，导入到Eclipse时提示The project was not built since its build path is incomplete. Cannot find the class file for java.lang.Object. Fix the build path then try building this project的提示，这样的错误一般是Java的JRE没有正确加载，当然了对于Android来说相关的SDK库也没有正确加载，解决的方法很简单，通过Google推荐的Android项目导入方法即可解决，如下:

  在Eclipse菜单的File=>New=>Project选择Android=>Android Project 这一步时，选择Create project from existing source选项，这样设置Location为你要导入Android项目的路径即可。