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Short-Circuit Evaluation

Satyajeet Kadam
Ranch Hand

Joined: Oct 19, 2006
Posts: 224
As per K&M book , Short circuit operators are applied to boolean opernads.

Follwing link is shwows an example where && operator is applied on integer operands?

This example is


class ConditionalDemo1 {
public static void main(String[] args){
int value1 = 1;
int value2 = 2;
if((value1 == 1) && (value2 == 2)) System.out.println("value1 is 1 AND value2 is 2");
if((value1 == 1) || (value2 == 1)) System.out.println("value1 is 1 OR value2 is 1");


Q1)Why this operator is applied on integer operands?
Q2)Can you tell me working of &,&&,|,|| and also the difference in
each of them? with code?
Q3) Is there any trick to remmber this stuuf
Jeremy Botha
Ranch Hand

Joined: Feb 16, 2005
Posts: 125

In the example you've pased, the && and || operators are applying to boolean expressions.

== is the equality operator; it evaluates the left and right hand operands, returning true if they are equal or false otherwise.

So, the expressions you have listed reduce as follows:


with regards to Q2:

& and | are bitwise operators, whereas && and || are boolean operators.

& and | apply at the bit level of the operands; that means that they evaluate every bit of the lhs operand against the corresponding bit in the rhs operand:

will print out

You can easilly check the above results by writing out the binary representation of 3 and 7, then doing bitwise anding and oring between the digits.

Q3: Not really, it's just something you should know.


McFinnigan? Never heard of him. Nobody here but us chickens...<br /> <br />SCJP for Java 1.4<br />SCJD for Java 5.0
Ernest Friedman-Hill
author and iconoclast

Joined: Jul 08, 2003
Posts: 24199

"&" and "|" can actually also be applied to boolean arguments, in which case they are equivalent to "&&" and "||" except that they don't do short-circuit evaluation: they always evaluate both arguments.

[Jess in Action][AskingGoodQuestions]
Jeremy Botha
Ranch Hand

Joined: Feb 16, 2005
Posts: 125

I agree. Here's the link:
subject: Short-Circuit Evaluation
jQuery in Action, 3rd edition