Did `if ( x = 0 )` was ever Java compilable

Question

I was intrigued that Scott Ambler in his book, Java Coding Standards, says, and I quote :

2.5.2 Place Constants on the Left Side of Comparisons

So he recommends to use
if ( 1 == something ) {…}    
if ( 0 = x ) { …}
instead of
if ( something == 1 ) {…}    
if ( x = 0 ) { …}  

OMG !!!

And he motivate this by saying that :

"Although they are both equivalent, at least on first inspection, the code on the left compiles and the code on the right does not."

As I'm aware (when I started programming Java, Java 14. was already in use), both of conditions will throw compiler error.

Starting from Ambler statement, I tried to search if Java syntax if ( x = 0 ); was ever compilable.

Can you help me out with this? I searched back different versions of JSR's and I did not find any change that could indicate that that piece of code was compiling on other java versions.

I compiled with a Jre7 compiler using target and source 1.2 and still raises compiler error. Unfortunately I don't have a Java 1.1 compiler: 9

My question is:

if(x = 0); Was compilable with older versions of Java compilers?

I'm confsed : Are you looking for this ?[Is there any difference between (null == var) and (var == null](http://stackoverflow.com/questions/18956526/is-there-any-difference-between-null-var-and-var-null/18956582#18956582) — Suresh Atta, Oct 16 '13 at 07:41
No, i don't think that was ever valid in Java - Java had a clear distinction between `boolean` and integral types from the very beginning. So this is just 13 year old crap (happens when someone mentally copy and pastes from his C experience without adjusting for the new language) — Gyro Gearless, Oct 16 '13 at 08:19
Yes, that's true, and more over, it not allows conversion from non-boolean to boolean or otherwise. But i wanted to find an explanation for Ambler statement, since is anyway, a heavy name in software engineering. It looks that he overlook this aspect. Anyway, i was negatively surprised by how many answers were out of scope. I would give u -1 to all if i could (except @GyroGearless) — Grandanat, Oct 16 '13 at 11:01

popfalushi · Answer 1 · 2013-10-16T07:42:44.273

5

it is not compilable. if (x=true) however still is if x is boolean.

edited Oct 16 '13 at 07:42

answered Oct 16 '13 at 07:37

popfalushi

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And even though it does compile, I wouldn't recommend that syntax ;) – Kayaman Oct 16 '13 at 07:44
Out of the scope of the question. -1 – Grandanat Oct 16 '13 at 15:00
@Grandanat both of mine and popfalushi are correct as per your question and it in in scope of the question.You need to modify your question and you dont know the meaning of -1 – SpringLearner Oct 17 '13 at 03:32

score 5 · Answer 2 · edited May 23 '17 at 10:29

5

This condition if ( x = 0 ) { …} if ( 0 = x ) { …} will never compile.It is because if accepts boolean type but x=0 are assignment operators

secondly 0=x is not right.0=x means that you are storing the value of x in 0 which can never be possible.

In this condition if ( something == 1 ) {…} instead of if ( 1 == something ) {…} is valid one and will work well with the present comparison with integers but for comparison between strings instead of == better use .equals() Please see this links to know difference between == and .eqauls() link1 link2

edited May 23 '17 at 10:29

Community

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answered Oct 16 '13 at 07:38

SpringLearner

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Well, the equals() doesn't really come into play here since we're comparing primitives, but yeah. – Kayaman Oct 16 '13 at 07:45
@Kayaman I agree with you thats why I used the word better.I had suggested for future if OP needs comparison in strings – SpringLearner Oct 16 '13 at 07:47
Out of the scope of the question. -1 – Grandanat Oct 16 '13 at 15:00
@GrijeshChauhan The link you gave is related with == but here Op's question is with = – SpringLearner Dec 30 '13 at 10:48

Did `if ( x = 0 )` was ever Java compilable

2 Answers2