OpenNLP

• provides several capabilities including classifiers, similar to NLP4J.

libsvm

• Old SVM library with interfaces to many programming languages.

Stanford Classifier 

• Requires Java (now Java 8). As well as API access, the program includes an easy-to-use command-line interface, ColumnDataClassifier, for building models. Its features are especially suited to building models over text data, but it also supports numeric variables.
• The Stanford Classifier is available for download, licensed under the GNU General Public License (v2 or later). Source is included. The Stanford Classifier code is dual licensed (in a similar manner to MySQL, etc.). Open source licensing is under the full GPL, which allows many free uses.