老的eclipse项目git clone下来，编译过但是运行异常；
java.lang.RuntimeException: Unable to instantiate activity
参考链接
https://stackoverflow.com/questions/4688277/java-lang-runtimeexception-unable-to-instantiate-activity-componentinfo 发现是eclipse项目 Propertis => Java Build Path => Source 选项缺少src目录，Add folders...加上就好了
