Java Programming - Java.lang Class - Discussion

11. 

What will be the output of the program?

public class ExamQuestion7 
{  
    static int j; 
    static void methodA(int i)
    {
        boolean b; 
        do
        { 
            b = i<10 | methodB(4); /* Line 9 */
            b = i<10 || methodB(8);  /* Line 10 */
        }while (!b); 
    } 
    static boolean methodB(int i)
    {
        j += i; 
        return true; 
    } 
    public static void main(String[] args)
    {
        methodA(0); 
        System.out.println( "j = " + j ); 
    } 
}

[A]. j = 0
[B]. j = 4
[C]. j = 8
[D]. The code will run with no output

Answer: Option B

Explanation:

The lines to watch here are lines 9 & 10. Line 9 features the non-shortcut version of the OR operator so both of its operands will be evaluated and therefore methodB(4) is executed.

However line 10 has the shortcut version of the OR operator and if the 1st of its operands evaluates to true (which in this case is true), then the 2nd operand isn't evaluated, so methodB(8) never gets called.

The loop is only executed once, b is initialized to false and is assigned true on line 9. Thus j = 4.


Stinger said: (Mar 18, 2011)  
Never heard of the term "non-shortcut version of the OR operator". Should be labeled "bitwise OR operator"?

Raj said: (Jun 5, 2013)  
Where j is initialized?

Costas said: (Jun 7, 2013)  
I agree this Raj. I think that this should produce a compilation error as j is never initialized and += operator is used.

Laughingpig said: (Oct 1, 2013)  
@Raj, Java guarantee class-level variables are initialized. int's are initialized to 0.

Sharad said: (Apr 2, 2014)  
Why methodB(8) never gets called?

Hemanth said: (Sep 8, 2014)  
Hi @Raj where local where b initialized.
In method methodA().

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