Android has moved away from ant and adopted gradle as its build system. I’m not very familiar with gradle but there is a feature of the new build system that makes it really appealing to migrate to it. The new gradle build system compiles libraries into an .aar (Android ARchive) which includes it’s resources and assets in a way that can be consumed by the apps that use your library.
This means you no longer need to copy the source code of the library into your project and compile both projects together, now you can just drop the .aar into your libs folder and it will work.
To use gradle with Android you need at least gradle version 1.10. I got the latest version at the time (1.12) and things worked fine for me.