Neuroph is lightweight Java neural network framework to develop common neural network architectures. It contains well designed, open source Java library with small number of basic classes which correspond to basic NN concepts. Also has nice GUI neural network editor to quickly create Java neural network components. It has been released as open source under the LGPL license, and it's FREE for you to use it.
H. Cruse, U. Steinkühler, and C. Burkamp. From Animals to Animats 5: Proceedings of the Fifth International
Conference on Simulation of Adaptive Behavior, (1998)