java-commons-collections4 4.1 Collections framework

The Java Collections Framework is the recognised standard for collection handling in Java. Commons-Collections seek to build upon the JDK classes by providing new interfaces, implementations and utilities. There are many features, including:

  • Bag interface for collections that have a number of copies of each object

  • BidiMap interface for maps that can be looked up from value to key as well and key to value

  • MapIterator interface to provide simple and quick iteration over maps

  • Transforming decorators that alter each object as it is added to the collection

  • Composite collections that make multiple collections look like one

  • Ordered maps and sets that retain the order elements are added in, including an LRU based map

  • Reference map that allows keys and/or values to be garbage collected under close control

  • Many comparator implementations

  • Many iterator implementations

  • Adapter classes from array and enumerations to collections

  • Utilities to test or create typical set-theory properties of collections such as union, intersection, and closure.