Any good overview out there on logical operators precedence?

[Marcus Jastrebowski]

Hello everybody,

I have been searching online but was not able to find a good summary of how exactly the logical operators precedence works in the absence of parentheses in complex logical expressions (combining short-circuit and non-short-circuit and everything else). Does anybody know where I can find this kind of detailed info?

I have been running and testing all kinds of weird scenarios, but still cannot figure out exactly how the compiler knows where to put the *implicit* parentheses. Here is one ridiculous example...

if (false || true || false && false | true || false && true)
  System.out.println("You win free beer!");
else
  System.out.println("You lose");

In real life I would kill anybody who uses expressions as complex as this one, AND does not use parentheses. But I have the feeling that the SCJP expects us to know...

So is there any good overview resource where the compiler precedence determination for complex logical statements is well summarized and documented???
[ November 21, 2007: Message edited by: Marcus Jastrebowski ]

[Marcus Jastrebowski]

Hmm...

Or perhaps I should assume that the exam does not test the operator precedence any more -- as the "Exam Watch" box on page 278 in Sierra/Bates says? ... Just thinking out loud here...

Any feedback, ideas?

[Jesper de Jong]

Google for "java operator precedence".

The Java Tutorials - Operators

[Marcus Jastrebowski]

Thanks for the link Jesper. I did google, but unsuccessfully. The table you are referring to does not even cover the non-short-circuit operators (| and &). And I am not sure if the precedence level of overloaded operations of "bitwise AND" and "bitwise inclusive OR" is the same as the non-short-circuit AND and OR logical operators.

Anybody else knows of any good comprehensive summary of short-circuit combined with non-short circuit behavior in complex logical expression in the absence of parentheses ?

Thanks much...

[Bert Bates]

Hey Marcus,

The older versions of the exam really pounded on the details of precedence - the newer versions of the real exam have de-emphasized that topic (preferring parens), but a lot of mock exam writers haven't kept up with those changes on the real exam, so you can still find a lot of mocks that go way overboard on this type of question.

Howver, you should still be really clear about short circuits!

hth,

Bert

[Marcus Jastrebowski]

Thank you Bert, I am sure that everybody is so glad to see the SCJP evolving to more closely represent the real life (on the job) situations...

Cheers,
Marcus

[Jesper de Jong]

Originally posted by Marcus Jastrebowski:
Thanks for the link Jesper. I did google, but unsuccessfully. The table you are referring to does not even cover the non-short-circuit operators (| and &). And I am not sure if the precedence level of overloaded operations of "bitwise AND" and "bitwise inclusive OR" is the same as the non-short-circuit AND and OR logical operators.

Hmmm, you're right, the boolean & and | are not included in that table. Have a look at this one: http://www.uni-bonn.de/~manfear/javaoperators.php

[Marcus Jastrebowski]

They do not like me over there Apparently, I can't get there from here:

Access forbidden!

You don't have permission to access the requested object on this server. Either you tried to access a directory that contains no index document or the specified object isn't readable.

In case you think this is a server error, please contact the Webmaster.

Error 403

RHRZ-Universitaet Bonn,

[Jan Nowak]

Here you have another table.

[Marcus Jastrebowski]

Awesome! Thank you Jan.