Collections Framework

A collection — sometimes called a container — is simply an object that groups multiple elements into a single unit.

Collections Framework :

A unified architecture for representing and manipulating collections.

All collections frameworks contain the following:

• Interfaces: Abstract data types that represent collections.
• Implementations: Concrete implementations of the collection interfaces. 
• Algorithms: These are the methods that perform useful computations, such as searching and sorting, on objects that implement collection interfaces. The algorithms are said to be polymorphic: that is, the same method can be used on many different implementations of the appropriate collection interface. In essence, algorithms are reusable functionality.

Benefits of the Java Collections Framework

• Reduces programming effort.
• Increases program speed and quality.
• Allows interoperability among unrelated APIs.
• Reduces effort to learn and to use new APIs.
• Reduces effort to design new APIs.