Q 12) Local And Instance Variables ?

	Local Variable	Instance Variable
01)	Local variables are the variables which are declared “ inside a Method or a Block “ .	Instance variables are the variables which are “ declared directly in a Class “.
02)	Local variables will not be initialized by the JVM, we will have to initialize it.	Instance variables will be initialized by the JVM, with their default values.
03)	Memory will be allocated for local variables when the corresponding block or a method is executed.	Memory will be allocated for the instance variables when an object is being created.

 

Example Programs of Instance And Local Variable :

Program 1 :

package org.javanoobs.variables;

public class Test {

     static int a,b; // static variable s

    

     public Test ( int a1, int b1){

          

           a = a1;

           b = b1;

     }

    

     public void disp (){

          

           System.out.println( " a = " +a);

           System.out.println( " b = " +b);

     }

    

    

     public static void main(String args[]){

          

           Test t1,t2;

          

           t1 = new Test(10,20);

           t2 = new Test (30,40);

          

           t1.disp();

           t2.disp();

     }

    

}

OUTPUT :

 a = 30

 b = 40

 a = 30

 b = 40

Program 2 :

package org.javanoobs.variables;

public class Test2 {

     int a,b;  // Instance variables

     static int c; //static variable.

    

     // Instance block..

     {

           System.out.println(" Inside Instance Block !!! ");

           System.out.println(" C " +c);

           System.out.println(" a " +a);

}

     static {

          

           System.out.println(" Static block is called !! ");

           System.out.println(" C " +c);

}

    

     // Create a method...

    

     public void disp(){

          

           int d = 1 ; // Local variable and

          

           d = a+b+c;

           System.out.println( " d after addition  " +d);

           System.out.println(" Disp method called... ");

     }

    

     public static void main(String args[]){

          

           Test2 t; // This is the reference variable.

          

           t = new Test2();

          

           t.disp();

          

     }

    

}

OUTPUT :

Static block is called !!

 C 0

 Inside Instance Block !!!

 C 0

 a 0

 d after addition  0

 Disp method called...