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Instance Variable in java – with java Program Example

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instance variable in java with example
instance variable in java with example

Hi Guys, Welcome to Proto Coders Point, In this tutorial we will discuss on what is instance variable java with an example.

Instance Variable java definition

An instance variable is declared in a class just outside the method, constructor, or block of code.

Basically, Java Instance Variable gets instantiated/created when an object of a class is created & destroyed when the object is destroyed. So we all know the class definition: An object is an instance of a class & every object has its own copy of the instance variable.

Point to remember about java instance variable

  1. Instance variable can be accessed only by creating an object.
  2. No need to set the value to an instance variable, by default “0” is set for number, “false” is set for boolean datatype & “null” is for object references.
  3. These are non-static variables.
  4. They are declared inside class just outside method, constructor & block.
  5. using the “new” keyword, when the object is created the class instance variable will also get created & when the object is destroyed even the instance variable gets destroyed.
  6. Initialization of class instance variable java can be done by using class object name as shown below.
Person p1 = new Person();

p1.name = "RAJAT PALANKAR";  //initialization value to variable

Instance Variable Java Example

class Person{
    //instance variable of class
    String name;
    int age;
}


public class Main
{
	public static void main(String[] args) {
	    
		//creating person1 Object
		Person p1 = new Person();
		p1.name="RAJAT PALANKAR";   // initializing value
		p1.age=25;
		
		
		//creating person1 Object
		Person p2 = new Person();
		p2.name="RAM PALANKAR";
		p2.age=25;
		
		//display data of person 2
		
	   System.out.println("Data of person 2");
	   System.out.println(p2.name);
	   System.out.println(p2.age);
	}
}

In above java code, example on instance variable, we have 2 variable in class person i.e. name & age. I have create multiple object by name p1 & p2, each object has it own copies of variable instance values.

output

Data of person 2   
                                                                                                           
RAM PALANKAR                                                                                                                  
25  

Introduction to java programming

Types of variable in java

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