Java Collections Framework provides a set of interfaces and classes that support the manipulation of collections of objects. This framework includes various types of collections like lists, sets, queues, and maps, which are designed to be flexible and efficient for different data manipulation tasks.

Key Components

Here are some of the key components of the Java Collections Framework:

  • List: An ordered collection of elements that allows duplicate values. ArrayList and LinkedList are the most commonly used implementations.
  • Set: A collection that contains no duplicate elements. HashSet, LinkedHashSet, and TreeSet are the common implementations.
  • Queue: A collection used to hold elements prior to processing. LinkedList, PriorityQueue, and ArrayDeque are common queue implementations.
  • Map: A collection that maps keys to values. HashMap, TreeMap, and LinkedHashMap are the common map implementations.

Common Collections Classes

  • ArrayList: Implements the List interface using an array.
  • LinkedList: Implements the List interface using a doubly-linked list.
  • HashSet: Implements the Set interface using a hash table.
  • LinkedHashSet: Implements the Set interface using a hash table and a doubly-linked list.
  • HashMap: Implements the Map interface using a hash table.
  • TreeMap: Implements the Map interface using a Red-Black tree.
  • LinkedHashMap: Implements the Map interface using a hash table and a doubly-linked list.

Useful Methods

Here are some of the most commonly used methods in Java Collections:

  • add(): Adds an element to the collection.
  • remove(): Removes an element from the collection.
  • contains(): Checks if an element is present in the collection.
  • size(): Returns the number of elements in the collection.
  • isEmpty(): Checks if the collection is empty.
  • clear(): Removes all elements from the collection.

For more information on Java Collections, you can refer to our comprehensive guide on Java Collections.

Java Collections Framework