This is a port of weka 3 ( see http://www.cs.waikato.ac.nz/ml/weka/ ) to the Android platform. Many things were removed (aka commented out), and 100% functionality is not promised. However, it's sure better than nothing.
for the lazy ones... download https://github.com/rjmarsan/Weka-for-Android/blob/master/wekaSTRIPPED.jar?raw=true and add it to your android project's build path. You may need to increase your heap size to get dx to convert it, but it will work.