java collection

Here we are going to learn about collection interface overview.

Whenever if you are asked a question about collection interface in an Interview you can remember this immediately by assuming that
you have list Of items to be purchased in a store, to purchase items you're standing in the queue and buying set of items
The set of items could be set of kitchenware items or set of electronic items and so on.


Since Java 1.2 version onwards Collection interface has been available in side Java.utill package.

Collection interface is the root interface for The following three interfaces.

1. set
2. list
3. Queue

These three interfaces are again classified as interfaces and Classes.

Set interface can be implemented or extended by following classes and interfaces.
1. HashSet class
2. Linked HashSet class
3. SortetSet sub interface
4. Navigable sub interface of SortedSet
5. TreeSet class


HashSet class has been available since from Java 1.2 version.
Linked HashSet class is a subclass of HashSet class And it has been available since from Java 1.4 version onwards.
TreeSet class implements sorted set interface or Navigable interface and it has been available since from Java 1.2 version onwards.

As we know that an interface or class can either be implemented or can be extended by another class or interface.

List interface can be implemented or extended by only following classes.
1. Array list
2. linked list
3. Vector
4. Stack

Array list is a class that implements list interface, It has been available since from Java 1.2 version onwards.
LinkedIn list is a sub Class of ArrayList and it is also available from 1.2 version.
Vector class is available from Java 1.0 version and it is a parent class for stack class.

Queue interface was introduced in Java 1.5 version and it is implemented by following interfaces and classes.
1.Blocking Queue
2.Priority blocking Queue
3.DeQueue
4.ArrayDeque
5.Blocking Dequeue
6.Linked blocking Deque

Blocking Queue is an interface that has been available from Java 1.5 and it is implemented by Priority blocking Queue.
DeQueue and blocking DeQueue are interfaces available from the Java 1.6 verson and these two interfaces are implemented by ArrayDeque and LinkedBlockingDeQueue
respectively.