What is collection in object oriented programing?

Answer 1

The Java Collection interface is the superinterface for any class in Java which represents a group of objects.

Some types of collections:

• Dequeues
  
• Lists
• Maps
• Queues
• Sets
• Stacks
• Vectors
  

Answer 2

The term Collection in OOP is a way to refer to a list of objects that the length can be changed dynamically by adding or removing elements from the lists. Unlike arrays, arrays have fixed sizes. However, sometimes arrays are included in the Collection context, because at a particular moment, the size of the collection is fixed anyway.

Or you may think of Collection is an interface of different kinds of data structures to hold 0 to many objects, whether they are Stack, Queue, Array, Dictionary, Hash Tables, etc.. They are collectively called Collections.

Answer 3

I believe that you are asking what is a collection, as in a java.util.Collection collection.

A collection is, at its most basic, a collection of Objects. There is a complete Collections framework, with different types of Collections. There are 3 basic types: List, Set, and Map. Lists are basically repurposed arrays, but they can do other things, such as LinkedList, which implements both the List and Queue interfaces. Sets are Lists that allow no duplicates, an important feature when working with databases. And finally, Maps are collections that maintain a one-to-one relationship between Keys and Values.

There are also other, lesser used but no less useful, types such as the Queue and the Stack.

And finally, although not a collection, is the humble array. Serving hordes of Java programmers since James Gosling had his first great Java brainwave, it provides a unchanging list. All of its functions and more are encapsulated in an ArrayList, which is recommended over arrays by many programming texts. An array is still useful, though.

Enjoy!