Google Guava is a java library with lot of utilities and reusable components.
This requires the library guava-10.0.jar to be in classpath.
The following example shows using Sets.symmetricDifference() API.
It returns an unmodifiable view of the symmetric difference of two sets.
//Returns a set containing all elements that are contained in either
//set1 or set2 but not in both
Set<String> resultSet = Sets.symmetricDifference(stringSet, stringSet2);