Install android platform on cordova

I started using PhoneGap and I got the following error when installing the android platform:

C: \ PhoneGap \ hello> cordova platform add android

[Error: An error occured falling on android establishment of sub-project. The specified access path was not found.]

somebody can give me help?? I have an windows 8 OS.

Please verify that you have java in your Environment Variable PATH. This causes this issue.