Class and Object

Class: a blue print or template for creating a type of objects. Object: an Instance of a class, also known as class object or class instance. It is made up of data and methods.

Declaration: Defines a variable’s name and type without assigning it a value. For objects, it means specifying the class type of the object reference name. Instantiation: The new keyword is used and memory is allocated for an object, the reference to the object is created and returned from the new keyword. Initialisation: The values put into the memory is allocated, this is what a constructor of a class does.

Initialisation process

The new keyword allocates memory for the person object. The constructor then initialise the newly allocated memory.

Default constructor

A default constructor is a no-argument constructor automatically provided by the Java compiler if no other constructors are explicitly defined in a class. The purpose of the default constructor is to ensure that every class has a constructor, allowing objects to be instantiated. Java takes back the default constructor once a constructor is explicitly defined by the programmer.

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Reference:

• https://stackoverflow.com/questions/15074083/difference-between-initializing-a-class-and-instantiating-an-object
• https://www.youtube.com/watch?v=N8IeMYsdgAY