Java - Java Collection Framework

What Is a Collection?

A collection, also known as a container, is an object that contains a group of objects.

Each object in a collection is called an element of the collection.

Architecture of the Collection Framework

The Collections Framework consists of three main components:

• Interfaces
• Implementation Classes
• Algorithm Classes

Interface

An interface represents a specific type of collection in the framework.

There is one interface defined for every type of collection in the framework.

• List interface represents a list.
• Set interface represents a set.
• Map interface represents a map.

Implementation

The Collections Framework provides implementations of collection interfaces.

The following code shows how to use the implementation class ArrayList to create a list.

Create an instance of the ArrayList class storing the reference in a variable of the List interface

List<String> names = new ArrayList<>();

Algorithm

To perform different actions on a collection, such as

• searching through a collection,
• converting a collection of one type to another type,
• copying elements from one collection to another,
• sorting elements of a collection in a specific order, etc.

Use algorithm classes on your collections.

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