Inheritance interview programming questions : Part 2

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 show() 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 show() method called");
7.  
8. }
9.  public static void main(String args[]){
10.  
11. SuperDemo supobj= new SuperDemo();
12.  supobj.show(); 
13.  
14. }
15. }

1. Super class show() method called

2. 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 show() 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 show() method called");
7.  
8. }
9.  public static void main(String args[]){
10.  
11. SuperDemo supobj= new SuperDemo();
12.  supobj.show(); 
13.  
14.  SubDemo subobj=new SubDemo();
15.  subobj.show();
16.  
17.  }
18. }

1. Super class show() method called
2. Sub class show() method called

3. 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 show() 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 show() method called");
7.  
8. }
9.  public static void main(String args[]){
10.  
11. SuperDemo supobj= new SubDemo();
12. supobj.show(); 
13.  
14. }
15. }

1. Sub class show() method called

4. 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 show() method called");
8.  
9. }
10.  
11.  public void superMethod(){
12.  
13.         System.out.println("Super class superMethod() called");
14.  
15. }
16.  
17. }

1. package com.instanceofjava;
2. public class SubDemo extends SuperDemo{
3. 
   
4. public void show(){
5.  
6.  System.out.println("Sub class show() method called");
7.  
8. } 
9.  
10. public void subMethod(){
11.         System.out.println("Sub class subMethod() called");
12. }
13. 
    
14.  public static void main(String args[]){
15.  
16. SuperDemo supobj= new SubDemo();
17. supobj.superMethod();
18.  
19. // supobj.subMethod();  // compile time error: The method subMethod() is undefined for the
20. type Super
21. 
    
22.  ((SubDemo)supobj).subMethod();
23. ((SuperDemo)supobj).show();
24. }
25. }

1. Super class superMethod() called
2. Sub class subMethod() called
3. Sub class show() method called