Java OCA OCP Practice Question 448

Question

What will the following code print when run without any arguments ... 

public class Main  { 

    public static int m1 (int i){ 
        return ++i; 
    } /* w ww  .j a v  a2s . c  om*/
     
    public static void main (String [] args)  { 

        int k = m1 (args.length); 
        k += 3 + ++k; 
        System.out.println (k); 
     } 

}

Select 1 option

  • A. It will throw ArrayIndexOutofBoundsException.
  • B. It will throw NullPointerException.
  • C. 6
  • D. 5
  • E. 7
  • F. 2
  • G. None of these. 


Correct Option is  : C

Note

When the program is run without any arguments, args gets assigned a string array of size 0.

So NullPointerException or ArrayIndexOutofBoundsException are out of question.

Thus, the first call becomes : 

int k = m1 (0);

Follow through the code like this:

1. Method m1() uses pre-increment operation. Therefore, first i is incremented and then the new value of i is returned.

2. Thus, k gets the value of 1.

3. Expand the += operator as: 

k = k + 3 + ++k;

This becomes (remember that k = 1 at this point): 

k = 1 + 3 +  (++k) i.e. 
k = 1 + 3 + 2; 
(at this point value of k is 2 because of ++k).

But the value of Right Hand Side has not yet been assigned to k.

k = 6; 6 is assigned to k thereby overwriting the value of 2.

Therefore, the final value of k is 6.




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