Unsupported major.minor version 51.0

android的5.0sdk出来了，本来想试试的，但是总是会出现Unsupported major.minor version 51.0或者是The project target (Android 5.0) was not properly loaded.。原来android5.0的运行环境必须是jdk1.7以上。这是在stackoverflow上看到的：

So basically you must have compiled your code with a higher version and trying to run it using a lower version.

原因是你用较高的版本编译，而运行环境是较低版本，于是造成了这种错误，所以还是升级jdk吧。