JCombinatorics provides useful combinatorics algorithms (permutations & combinations) and functions for Java.

Usage

Using Maven, add the following to your pom.xml

<repositories>
  <repository>
    <id>maven2.github.com</id>
    <url>http://maven2.github.com</url>
  </repository>
</repositories>
<dependencies>
  <dependency>
  	<groupId>jcombinatorics</groupId>
  	<artifactId>jcombinatorics</artifactId>
  	<version>0.3</version>
  </dependency>
</dependencies>