Collections

A collection is simply an object that groups multiple elements into a single unit. Collections are used to store, retrieve, manipulate, and communicate aggregate data. Typically, they represent data items that form a natural group, such as a poker hand (a collection of cards), a mail folder (a collection of letters), or a telephone directory (a mapping of names to phone numbers).

What is a Collections framework?

A collections framework is a unified architecture for representing and manipulating groups of data as a single unit collection. All collections frameworks consist of the following parts:

• Interfaces: The Java collections framework interface provides the abstract data type to represent a collection. The root interface of Collections framework hierarchy is java.util.Collection. Some other important interfaces are java.util.List and java.util.Set. All the collections framework interfaces are present in the java.util package.
• Implementations: These are the core implementations...