What is the difference between class object and class instance?

The object a particular class is referred to as its instance. The object created gains all the features and behavior of its parent class, hence acts as a replica or instance of that class. For ex: [code] public class Animal{   //This is a class //Declarations and Definitons } Animal dog = new Animal(); //This is an instance of Animal class [/code]

Instance of a class is nothing but an object of a class Eg:- MyObject mobject= new MyObject(); Here you have created an instance(object) of MyObject using new operator which is pointed by mobject reference variable. Instance variables are states of the object i.e; what an object has. Eg:- Class MyObject { String name; // name is instance variable with value null int length; // length is instance variable with value 0 }

Instance variable of a class is like a person have mobile and instance of a class is like Rohan is a person. If you can say in one line is like Rohan is a person who have mobile phone. Now you can relate Person with class, mobile phone with instance variable of Person and Rohan with instance of class Person.

An instance variable is a variable whose separate copy is available to each object. A class variable is a variable whose single copy in memory is shared by all objects. Instance variables are created in the objects on heap memory. Class variables are stored on method area.

object" and "instance" are the same thing. There is a "class" that defines structure, and instances of that class (obtained with new ClassName()). For example there is the class Car, and there are instance with different properties like mileage, max speed, horse-power, brand, etc. Reference is, in the Java context, a variable* - it is something pointing to an object/instance. For example, String s = null; - s is a reference, that currently references no instance, but can reference an instance of the String class. Going outside the world of programming for a second: you know what people are. You are an "instance" of the class "people" - I can talk about people in general (the class of objects), or if I have a specific one in mind, I talk of an "instance". An instance can have properties that are not automatically a consequence of being a member of the class. All humans have a heart, but not all humans have your name and date of birth. I hope that clears it up a bit?

In your example, testClass is the "instance of Class" and "Object" also. In short, instance of a class and object are one and the same. Instance variable and Object are the same. Even if you are talking with reference to the normal variables it's still the same. Everywhere in Java, we create objects of the internal classes.

Class and variable types are abstractions that describe a data structure. You can assign values to these abstractions. You need to instantiate them as objects (for class) and variables (for variable types) before you can do so.

Think of classes as blueprints and objects / instances as actual individual manifestation of the blueprint. Like a blueprint for a house and the actual buildings. Any number of buildings can be built based on the same blueprint.  However these buildings can have differences from each other. Represented by different values of the instance variable. For example the adress, number of windows etc. Counter to these attributes are the class variables, which always hold the same value for objects of a class. These are are used to for example count the number of objects of same class.

First be clear of what is instance of class and instance variable. class A {   int instanceVar;   public static void main(String args[])  {       A obj=new A();       obj.instanceVar=10;   } } 1.here when you say new you are allocating memory for the object hence instantiating the object, so obj will be instance of class. There are Types of variables in java a.This class may have some methods and variables libe instanceVar. This are different values for each object and hence are called instance variables. b.class variables are global to class.They belong to entire set of class and hence has only one memeory location. c.local variables are the once within function ie. the once whose scope is local.