Inheritance programming interview questions

1. what is the output of following program:

1. package com.instanceofjava;
2.  
3. public class SuperDemo{
4. 
   
5. public void show(){
6.  
7.   System.out.println("super class method called");
8.  
9. }
10.  
11. }

1. package com.instanceofjava;
2. public class SubDemo extends SuperDemo{
3. 
   
4. public void show(){
5.  
6.   System.out.println("sub class method called");
7.  
8. }
9.  public static void main(String args[]){
10.  SubDemo subobj=new SubDemo();
11.  subobj.show();
12. }

1. sub class method called

2. what is the output of following program:

1. package com.instanceofjava;
2.  
3. public class SuperDemo{
4. 
   
5.  int x;
6. 
   
7. }

1. package com.instanceofjava;
2. public class SubDemo extends SuperDemo{
3.  
4.  int y;
5.  
6. public void show(){
7.  
8.  super.x=y+2;
9.   System.out.println("x="+super.x+"y="+y);
10.  
11. }
12.  
13.  public static void main(String args[]){
14.  
15.  SubDemo subobj=new SubDemo();
16.  subobj.show();
17.  
18. }

1. x=2 y=0

3. what is the output of following program:

1. package com.instanceofjava;
2.  
3. public class SuperDemo {
4. 
   
5.  int x;
6. 
   
7. }

1. package com.instanceofjava;
2.  
3. public class SubDemo extends SuperDemo{
4.  
5.  int y;
6.  
7. public void show(){
8.  
9.  super.x=y+2;
10.   System.out.println("x="+super.x+"y="+y);
11.  
12. }
13.  
14.  public static void main(String args[]){
15.  
16.  SubDemo subobj=new SubDemo();
17.  subobj.x=2;
18.  subobj.y=2;
19.  subobj.show();
20.  
21. }

1. x=4 y=2

4. what is the output of following program:

1. package com.instanceofjava;
2.  
3. public class SuperDemo{
4. 
   
5.  int x;
6. SuperDemo(){
7.  
8.  x=24;
9. 
   
10. }
11. }

1. package com.instanceofjava;
2. public class SubDemo extends SuperDemo{
3.  
4.  int y;
5.  
6. public void show(){
7.  
8.   System.out.println("x="+super.x);
9.   System.out.println("y="+y);
10.  
11. }
12.  
13.  public static void main(String args[]){
14.  
15.  SubDemo subobj=new SubDemo();
16.  subobj.show();
17.  
18. }

1. x=24
2. y=0