Reference android.target.classpath not found

I'm working on an Ant script for an 开发者_Go百科Android build, but am coming up against the error

Reference android.target.classpath not found

I can't find any information on what android.target.classpath is or where it is set. Does anyone know?

With SDK revision 20, the new name of former android.target.classpath is project.target.class.path.

It must be really funny for Android engineers to break the build.xml API with every release.

it is in buit android.jar file class information.not your bug.it is good habit to find bug from logcat