The Collection Classes:
Java provides a set of standard collection classes that implement Collection interfaces. Some of the classes provide full implementations that can be used as-is and others are abstract class, providing skeletal implementations that are used as starting points for creating concrete collections.
The standard collection classes are summarized in the following table:
SN Classes with Description
Implements most of the Collection interface.
Extends AbstractCollection and implements most of the List interface.
Extends AbstractList for use by a collection that uses sequential rather than random access of its elements.
Implements a linked list by extending AbstractSequentialList.
Implements a dynamic array by extending AbstractList.
Extends AbstractCollection and implements most of the Set interface.
Extends AbstractSet for use with a hash table.
Extends HashSet to allow insertion-order iterations.
Implements a set stored in a tree. Extends AbstractSet.
Implements most of the Map interface.
Extends AbstractMap to use a hash table.
Extends AbstractMap to use a tree.
Extends AbstractMap to use a hash table with weak keys.
Extends HashMap to allow insertion-order iterations.
Extends AbstractMap and uses reference equality when comparing documents.
The AbstractCollection, AbstractSet, AbstractList, AbstractSequentialList and AbstractMap classes provide skeletal implementations of the core collection interfaces, to minimize the effort required to implement them.