Abstract Data Types

An Abstract Data Type (ADT) defines the operations and behaviour of a data structure, but not the implementation.

Multiple data structures may be used to implement the same ADT.

For example, a Stack is an Abstract Data Type with the following operations:

• push()
• pop()
• peek()
• isEmpty()

We can implement a Stack by using a static array or an ArrayList.

A queue is another ADT with the following operations:

• enqueue()
• dequeue()
• peek()
• isEmpty()

We can also implement a Queue by using a static array or an ArrayList.

In this unit we will study a variety of Abstract Data Types and their implementations.