How to read this if statement?

[jeroenvanveghel]

I have encountered an if-statement in a way I'm unfamiliar with.
After some googling I can't find a answer that's why I'm asking it here.

boolean onlyNots;
Long bonnr;

return ( onlyNots ? bonnr==0 : bonnr != 0 );

Can anyone explain to me what the '?' and the ':' means? And how I'm supposed to read this statement?
When does it return true, when does it return false?

Many thanks in advance!

[JosAH]

It's a ternary expression; its general form is <condition>?<if_true>:<if_false>; if <condition> is true then the value of the entire expression is <if_true>, otherwise the value is <if_false>. In your example the value of the entire expression depends on onlyNots; if it is true the value of the entire expression is bonnr==0 (that is either the value true or false); if the value of onlyNots is false the value of the entire expression is bonnr != 0 (which is also true or false. The return statement could've been written as:

if (onlyNots)
   return bonnr == 0;
else
   return bonnr != 0;

kind regards,

Jos

[jeroenvanveghel]

Thank you for the nice explanation, I'm understanding it now!

[Iron Lion]

Alternatively, the expression could simply have been replaced with:

return onlyNots == (bonnr == 0);

[JosAH]

Alternatively, the expression could simply have been replaced with:

return onlyNots == (bonnr == 0);

That is 'simply' after a Karnaugh map has been scrutinized and solved ;-)

kind regards,

Jos

[Mr777]

It's also called the Conditional expression, and it behaves as simple if-else. As well defined by JosaH, it has three parts so it's called ternary condition or ternary operator.
It's general syntax is

(condition)?TruePart:FalsePart;