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javabitwise-operators

Why do we usually use || over |? What is the difference?

I'm just wondering why we usually use logical OR || between two booleans not bitwise OR |, though they are both working well.

I mean, look at the following:

if(true  | true)  // pass
if(true  | false) // pass
if(false | true)  // pass
if(false | false) // no pass

if(true  || true)  // pass
if(true  || false) // pass
if(false || true)  // pass
if(false || false) // no pass

Can we use | instead of ||? Same thing with & and &&.

Solution

  • If you use the || and && forms, rather than the | and & forms of these operators, Java will not bother to evaluate the right-hand operand alone.

    It's a matter of if you want to short-circuit the evaluation or not -- most of the time you want to.

    A good way to illustrate the benefits of short-circuiting would be to consider the following example.

    Boolean b = true;
if(b || foo.timeConsumingCall())
{
   //we entered without calling timeConsumingCall()
}

    Another benefit, as Jeremy and Peter mentioned, for short-circuiting is the null reference check: 

    if(string != null && string.isEmpty())
{
    //we check for string being null before calling isEmpty()
}

    more info