Question

class Upper { private int i;

private String name; public Upper(int i){ name = "Upper";

this.i = i;}

public void set(Upper n){ i = n.show();} public int show(){return i;}

}

class Middle extends Upper { private int j;

private String name; public Middle(int i){

super(i+1);

name = "Middle"; this.j = i;}

public void set(Upper n){ j = n.show();} public int show(){return j;}

}

class Lower extends Middle { private int i;

private String name; public Lower(int i){

super(i+1); name = "Lower"; this.i = i;}

public void set(Lower n){ i = n.show();} public int show(){return i;}

}

class Tester {

public static void main(String[] args){ Lower a = new Lower(1);

Middle b = a;

Upper c = new Middle(5);

System.out.println(a.show()); System.out.println(b.show()); System.out.println(c.show());

a.set(c);

b.set(a);

c.set(b);

System.out.println(a.show()); System.out.println(b.show()); System.out.println(c.show());

}

}

1. What is printed as a result of the first occurrence of System.out.println(a.show());? Answer is 1
2. What is printed as a result of the first occurrence of System.out.println(b.show()); Answer is 1
3. What is printed as a result of the first occurrence of System.out.println(c.show()); Answer is 5
4. What is printed as a result of the second occurrence of System.out.println(a.show()); after the set commands? Answer is 1
5. What is printed as a result of the second occurrence of System.out.println(b.show()); after the set commands? Answer is 1
6. What is printed as a result of the second occurrence of System.out.println(c.show()); after the set commands? Answer is 1

Answers of the questions are given but i am not understanding the reason behind. I would appretiate if you explain in detail.

Answer 1

1 What is printed as a result of the first occurrence of System.out.println(a.show());? Answer is 1

This statement will call the method in show() in Lower class so it will return 1 as we passed 1 as argument while creating the object

2 What is printed as a result of the first occurrence of System.out.println(b.show()); Answer is 1

This statement will call the method in show() in Lower class so it will return 1 as we passed 1 as argument while creating the object

3 What is printed as a result of the first occurrence of System.out.println(c.show()); Answer is 5

This statement will call the method in show() in Upper class so it will return 5  as we passed 5 as argument while creating the Upper object

after calling the setters we passed the objects and it sets the values to 1

so after that it will print all 1