What is difference between instance variable and class variable in java?

Answer 1

The main difference between the class variable and Instance variable is,

first time, when class is loaded in to memory, then only memory is allocated for all class variables. Usually static variables are called class variables. These variables are available throughout the execution of the application and the values are common to the class. You can access them directly without creating an object of the class.

Instance variables are normal variables declared in a class, that would get initialized when you create an instance of the class. Every instance of the class would have a copy of the variable and you need a class instance (object) to access these variables

Answer 2

Well, at the basic level, class fields, or static fields, as they are called sometimes, belong to the class and not to any particular instance of the class. Class fields can be assigned without instantiation of instance objects of a class. For example:

public class ExampleClass {

public static String classField = "";

public String instanceField = "";

}

I can assign a value to classField just like that:

ExampleClass.classField = "new value";

Instance fields, on the other hand, belong to a particular instance of the class. Thus, to assign an instance field a value, you have to first instantiate an object of the class just like that:

ExampleClass obj1 = new ExampleClass();

obj1.instanceField = "new value";

Answer 3

Static Variables or Class Variables

The static modifier tells the system that this particular variable belongs to the class and does not belong to any specific instance of the same. The class will contain only one instance of the static variable irrespective of how many objects of the class you create.

Instance Variables

The instance variables dont belong to the class but instead are mapped to every single instance of the class object.

Ex:

public class Test {

private static String var = "AAA";

private int n = 10;

}

in the code above var is a class variable whereas n is an instance variable

Answer 4

In java, any variable marked as a static is considered a variable owned by the class. Even if you have a bunch of instances of this class, you only will have one copy of your static variable shared by all the instances.

This is the main difference with instance variables where each instance of your class have his own variables.

Example, if you have a class like this:

public class SoldCar{

public String model; //instance variable - each soldCar have its model

public int cost; //instance variable - each soldCar have its cost

public static int count; //class variable - all soldCars share this count

public SoldCar(){

count ++;

}

public static void main(String[] args){

SoldCar ferrari = new SoldCar();

ferrari.model = "fiorano";

ferrari .cost = 999999;

SoldCar beetle = new SoldCar();

beetle.model = "new beetle";

beetle.cost = 2222;

System.out.println( ferrari.model + "," + ferrari.count );

System.out.println( beetle.model + "," + beetle.count );

}

}

The output of this program is :

fiorano,2

new beetle,2

Answer 5

Instance Variable: These are the normal variables that you declare within a class. These variables are tagged to a particular object instance of the class.

Class Variables: These are the static variables that you declare within a class. These variables are not tagged to a particular object instance of a class and no matter how many object instances get created for a class, only one instance of the static variable gets created.

Answer 6

instance variables:the variables which are declared in class

these variables can have access modifiers

local variables: the variables which are declared in method

these variables should not have access modifiers/specifiers except final

answer by divya puvvada