What are the Core collection interfaces in Java

The Java Collection framework offers a comprehensive set of interfaces and class implementations that facilitate efficient and meaningful data manipulation. At the apex of the collection hierarchy is the Collection Interface, which serves as a fundamental contract for implementing collection-related operations.

While Java does not provide a direct implementation of the Collection framework, the Collection Interface itself is implemented by two important classes: List and Set.

The core collection interfaces within the Java Collection framework are as follows:

  1. List: The List interface extends the Collection interface and represents an ordered collection of elements. Lists allow duplicate elements and maintain the insertion order. Common implementations of List include ArrayList, LinkedList, and Vector.
  2. Set: The Set interface, also an extension of the Collection interface, represents a collection that does not allow duplicate elements. Sets typically do not maintain a specific order of elements. Notable implementations of Set are HashSet, TreeSet, and LinkedHashSet.
  3. Queue: The Queue interface defines a collection that represents a waiting area, where elements are inserted at one end and removed from the other. Queues follow the First-In-First-Out (FIFO) principle. Notable implementations of Queue include LinkedList and PriorityQueue.
  4. Deque: The Deque interface extends the Queue interface and represents a double-ended queue, allowing elements to be inserted and removed from both ends. Deques support operations at both ends, enabling flexibility in data handling. Common implementations of Deque include ArrayDeque and LinkedList.
  5. Map: The Map interface represents a mapping between unique keys and corresponding values. It does not extend the Collection interface but is an important part of the Java Collection framework. Maps do not allow duplicate keys and are commonly used for key-value pair associations. Notable implementations of Map include HashMap, TreeMap, and LinkedHashMap.

These core collection interfaces provide a standardized and consistent approach to handling and manipulating collections of data in Java.