Static in Java

1. class Test1 {

   public

       static void main(String[] args)

       {

           int x = 20;

           System.out.println(x);

       }

       static

       {

           int x = 10;

           System.out.print(x + " ");

       }

   }

• 10 20

• 20 10

• 10 10

• 20 20

class Test1 {

    static int x = 10;

public

    static void main(String[] args)

    {

        Test1 t1 = new Test1();

        Test1 t2 = new Test1();

  

        t1.x = 20;

        System.out.print(t1.x + " ");

        System.out.println(t2.x);

    }

}

• 10 10

• 20 20

• 10 20

• 20 10

Answer explanation

static variable is class level variable. if we do update in any reference then automatically all pointing reference value are changed.

class Test1 {

    int x = 3;

public

    static void main(String[] args)

    {

        System.out.println(x);

    }

    static

    {

        System.out.print(x + " ");

    }

}

• 3 3

• Error

• Exception

• None

Answer explanation

If we are trying to print the instance variable inside the static block or static method without creating class instance then it will give the error : non-static variable x cannot be referenced from a static context.

class Test1 {

    static int i = 1;

public static void main(String[] args)

    {

        int i = 1;

        for (Test1.i = 1; Test1.i < 10; Test1.i++) {

            i = i + 2;

            System.out.print(i + " ");

        }

    }

}

• 1 3 9

• 1 2 3 … 9

• 3 5 7 9 11 13 15 17 19

• None

Answer explanation

Here, two different i copies of variable are declared, one is static and other one is local. If we write Test1.i then, static variable is executed and if we write only i, then local variable are executed.

class Test1 {

    static int i = 1;

public static void main(String[] args)

    {

        for (int i = 1; i < 10; i++) {

            i = i + 2;

            System.out.print(i + " ");

        }

    }

}

• 3 6 9

• 3 6 9 …. 27

• Error

Answer explanation

Here local variables are printed after execution. If we want to execute static variables, then we write Test1.i or we write Test1 object.i.

1. class overload

2. {int x;

3. int y;

4. void add(int a){

5. x = a + 1;

6. }

7. void add(int a, int b){

8. x = a + 2;

9. }}

10. class Overload_methods{

11. public static void main(String args[]){

12. overload obj = new overload();

13. int a = 0;

14. obj.add(6);

15. System.out.println(obj.x);

16. }

17. }

• 5

• 6

• 7

• 8

1. class overload{

2. int x;

3. double y;

4. void add(int a , int b){

5. x = a + b;}

   void add(double c , double d){

6. y = c + d;}

7. overload(){

8. this.x = 0;

9. this.y = 0;

10. }

11. }

12. class Overload_methods{

13. public static void main(String args[]){

14. overload obj = new overload();

15. int a = 2;

16. double b = 3.2;

17. obj.add(a, a);

18. obj.add(b, b);

19. System.out.println(obj.x + " " + obj.y);

20. }

21. }

• 6 6

• 6.4 6.4

• 6.4 6

• 4 6.4

1. class A

2. {

3. int i;

4. public void display()

5. {

6. System.out.println(i);

7. }

8. }

9. class B extends A

10. {

11. int j;

12. public void display()

13. {

14. System.out.println(j);

15. }

16. }

17. class Dynamic_dispatch

18. {

19. public static void main(String args[])

20. {

21. B obj2 = new B();

22. obj2.i = 1;

23. obj2.j = 2;

24. A r;

25. r = obj2;

26. r.display();

27. }

28. }

• 1

• 2

• 3

• 4

Answer explanation

r is reference of type A, the program assigns a reference of object obj2 to r and uses that reference to call function display() of class B.