Anatomy of a Class

Anatomy of a Class

Understanding Class Structure

A class in Java is a blueprint for creating objects.
It contains variables and methods that describe what the objects made from this class can do.

Key Components of a Class

The class name: This is the identifier that is used to create objects. The class name should be descriptive.
The class body: This is enclosed by braces {} and contains all the code that provides for the structure and behaviour of the objects formed from this class.

Class Declaration Format

The format typically is:

public class ClassName {
  // variables
  // methods
}

Here, public is an access modifier. Classes can also be declared as private or protected.

Instance Variables

Also known as fields, these are variables declared within a class, outside any method, and they are available to all methods in the class.
Each object will have its own set of instance variables.
They represent the properties of an object created from that class and can be of any data type (int, float, boolean, etc.).

Methods

Methods are basically a collection of statements that perform some operation.
They define the behaviour of objects of the class.
Methods can perform functions, return values, and use parameters to accept input.

Constructors

A constructor is a special type of method that is used to initialise objects.
The constructor is invoked when a new object is created.
The name of the constructor must be the same as the class name.

For example:

public class ClassName {
  // constructor
  ClassName() {
      //initialise
  }
}

Constructors can have parameters, and there can also be multiple constructors with different parameters (known as constructor overloading).

Importance of Class

A class is a basic unit of Encapsulation, one of the four principles of Object Oriented Programming (OOP).
With a class, it’s possible to encapsulate information and keep it from being altered or accessed unintentionally, promoting data security.
Understanding the anatomy of a class helps in the organised coding and designing of complex software applications, following the principles of OOP.