Apache-Commons-Collections

The Apache Commons ComparatorUtils provides utils for creating and using comparators from org.apache.commons.collections4.comparators package.

The Apache Commons Collections SetUtils class has utility methods and decorators for Set and SortedSet instances.

In this post, we will explore all the utility methods and decorators for List instances in the Apache Commons Collections ListUtils class.

The Apache Commons BidiMap (a bidirectional map) is an interface using which we can perform a lookup on a map in either direction.