Exceptions

[Kudret Serin]

Hi,

  
Which of the following may throw an exception?  
1 if ((s !=null) | (  i =s.length()))    
2 if ((s ==null) | (  i =s.length())) 
3 if ((s !=null) || (  i =s.length()))
4 if ((s ==null) || (  i =s.length()))
             
 
Select all best answers?  
 

A.    1 
B.    2 
C.    3 
D.    4 
 

Can anybody please explain the idea?
Thanks.

PS: The 27. question from http://home-1.tiscali.nl/~bmc88/java/q_a/index.html#qa

[Sergei Iakhnin]

My answer is a), b), c).

a) and b) because the | always evaluates both operands so if s is null s.length() will throw NullPointerException

c) because if s == to null then (s != null) will evaluate to false and consequently s.length() will throw NullPointerException.

Not d) because if s == null then || operator will short cirquit and not evaluate the second operand and if s != null then s.length() will not throw an exception.

[Barry Gaunt]

The main point in this question is to understand the difference between the '|' operator and the '||' operator. Once you understand the difference, the solution to the problem is plain sailing.

[sandeep dhingra]

|| is a short circuit operator that is if the first operation comes to true it will not go to the second one so a,b,c will give exceptions

[R Sawant]

Hi all,
'|' is a binary bitwise or operator. Both the operands should be either boolean or integrals. Operands cannot be boolean & integers at the same time.
In the options given by u left operand is boolean while right operand is integer. This will give compiler error.
Same applies for the '||' operator.



Ramdas.