Package org.apache.commons.collections4.multimap

This package contains implementations of the MultiValuedMap interfaces. A MultiValuedMap holds a collection of values against each key.

The following implementations are provided in the package:

  • ArrayListValuedHashMap - ListValuedMap implementation using a HashMap/ArrayList
  • HashSetValuedHashMap - SetValuedMap implementation using a HashMap/HashSet

The following decorators are provided in the package:

  • Transformed - transforms elements added to the MultiValuedMap
  • Unmodifiable - ensures the collection cannot be altered