Question

Code Design 1 : works perfectly

 public static void main (String[] args)
    {       
        recursion(2);       
    }

    public static void recursion(int num)
    {
        if (num > 0)
        {
            recursion( num - 1 );
            System.out.println(num);
        }   
    }

Code Design 2 : Infinite Loop. ?

public static void main (String[] args)
    {       
        recursion(2);       
    }

    public static void recursion(int num)
    {
        if (num == 0) return;
        while (num > 0)
        {
            recursion( num - 1 );
            System.out.println(num);
        }   
    }

1. Can someone plz help me in understanding why 2nd design is getting
   into infinite loop?
2. I have already put return in 2nd design . So it should have worked
   fine. Also can you plz give me explanation in detail?

Answer 1

1. First of all if is Not a Loop, we only have for loop, for-each, while loop and do-while loop.

2. The reason for the 2nd code to go in for a Infinite loop is that, you are never decrementing the value of num.

Do this….

while (num > 0)
    {
        recursion( num - 1 );
        System.out.println(num);
        num = num - 1;           // Decrementing the value of num by 1
    }