How does omitting curly braces in Java program effect the code

Question

I've searched for this, but couldn't find an answer and for whatever reason I was too ashamed to ask professor, due to that feeling when hundreds of people stare at you...

Anyhow, my question is what's the importance of having brackets? Is it OK if I omit them? Example:

for (int i = 0; i < size; i++)  {
   a += b;
}

vs

for (int i = 0; i < size; i++)
   a += b;

I know both of them will work, but if I omit the brackets (which I tend to do a lot, due to visibility) will that change anything, anything at all? As I said, I know it works, I tested it dozen of times, but now some of my uni assignments are getting larger, and for some reason I have irrational fear that in the long run, this my cause some problems? Is there a reason to fear that?

Answer 1

Using braces makes the code more maintainable and understandable. So you should consider them by default.

I sometimes skip using braces on guard clauses to make the code more compact. My requirement for this is that they're if statements that are followed by a jump statement, like return or throw. Also, I keep them in the same line to draw attention to the idiom, e.g:.

if (!isActive()) return;

They also apply to code inside loops:

for (...) {
  if (shouldSkip()) continue;
  ...
}

And to other jump-conditions from methods that are not necessarily at the top of the method body.

Some languages (like Perl or Ruby) have a kind of conditional statement, where braces don't apply:

return if (!isActive());
// or, more interestingly
return unless (isActive());

I consider it to be equivalent to what I just described, but explicitly supported by the language.