Object and Class:

OOPS (Object Oriented Programming System) is a programming approach which provides solution to problems with the help of algorithms based on real world. It uses real world approach to solve a problem.

Main Oops concepts are : 

• Inheritance
• Polymorphism
• Encapsulation
• Abstraction

Class : A class is declared using class keyword. A class is a blue print or set of instruction to bind the data with its related and corresponding functions. 

A Class can contain :-

1. Fields
2. methods,
3. constructors
4. objects 

Syntax: 

                                              

class <class_name>{      field;      method;  }

Object :

An object is an entity which contain state and behaviour. Object is nothing but instance of a class.
An object has three characteristics:

• State : represent state of an object.
• Behaviour: represent behaviour of an object. The functionalities associated with the object => Behavior of the object.
• Identity: represent identity of an object.

Ways to initialize an object : 

• Using New keyword
• Class.forName()
• Using Clone()
• Using Deserilization

For more details click here 

How a class is initialized in java?

A Class is initialized in Java when an instance of class is created using either new operator or using reflection using class.forName(). A class is also said to be initialized when a static method of Class is invoked or a static field of Class is assigned.