Short-Circuit Operators.....

[Mukti Bajaj]

Hello,
34. Given the following declaration which of the following statements equals to true
boolean b1 = true;
boolean b2 = false;
A) b1 == b2;
B) b1 | | b2;
C) b1 |& b2;
D) b1 && b2;
The answer to above questions is B...I think it should be B & D.
Can someone explain.....

[Jane Griscti]

Hi Mukti,
The surest way to check the results of Mock questions is to write some code and see what happens

public class Q34 {
    public static void main(String[] args) {
    
        boolean b1 = true;
        boolean b2 = false;
        
        System.out.println(" b1 == b2 \t" + (b1==b2) );
        System.out.println(" b1  | b2 \t" +  (b1 | b2) );
        System.out.println(" b1 & b2 \t" +  (b1 & b2) );
        System.out.println(" b1 && b2 \t" +  (b1 && b2) );
    
    }
}
Output:
C:\Java\Examples>java Q34
 b1 == b2       false      // not the same object
 b1  | b2       true       // at least one value is 'true'
 b1 & b2        false      // both values must be 'true'
 b1 && b2       false      // both values must be 'true'

The short-circuit operators give the same results as the normal | and & operators.
Hope that helps.

------------------
Jane
The cure for boredom is curiosity.
There is no cure for curiosity.
-- Dorothy Parker

[Vineet Sharma]

Hi Mukti,
I fully agree with you. D should be "true" since "b1" evaluates to true and because of the short circuit operator, the whole expression becomes true!

[Mukti Bajaj]

Hi Vineet,
The answer to the above question is only B and not D.
As for boolean OR operators, | and | | if either or both operands are true,the result is true and you will get result false, only if both the operands are false.
And for boolean AND operators, & and && if both the operands are true the result is true otherwise the result is false.
So, I agree with Jane suggestions....of writing the code and checking.
Good Luck!
Mukti