Better Java method Syntax? Return early or late? [duplicate]

Answer 1

The only time I would say you definitely shouldn't return early is if you can't easily see every return within a single screen (whatever the standard might be for people working on the same code base), you should at the very least be adding comments indicating that the function can return early if there is an early return.

The only time I would say you definitely should return early is if your code looks like...

boolean valid = true;
if( condition1 ) {
   valid = false;
}
if( valid ) {
   ...
   if( condition2 ) {
      valid = false;
   }
}
if( valid ) {
   ...
   if( condition3 ) {
      valid = false;
   }
}
... (etc)

If you find yourself in either of these situations, however... you should probably be refactoring the function.

Answer 2

As with most coding styles, it's really a matter of preference, but guard clauses are considered by many to be a best practice.

Answer 3

I prefer returning early and avoiding deep nesting. This is particularly true right at the start of the method: test anything that's simple, and get out (or throw an exception) if you can do so really early.

If it's right in the middle of a method, it's more of a judgement call.

Note that I'd refactor your example straight away to use a single if:

boolean validate(DomainObject o) {    
  if (o.property == x || o.property2 == y) {
     return true;
  } ...
  return false; 
}

I realise this was only a toy example, but my point is that it's always worth looking for more ways to simplify your code :)

Answer 4

There are two factors pulling against each other.

The first factor is ease of debugging. If you return immediately (as shown in your second code snippet), it sometimes becomes difficult to debug a big function since it is hard to find these return statements, specially if they were put there by mistake.

The second factor is ease of implementation. If you are checking basic correctness of arguments at the beginning of the function and there is a long piece of code before the function finishes, you might have to put that entire code in a condition loop. If you don't, at some point the argument might get used for some long calculation, wasting time, because it would ultimately be rejected anyways.

So, the answer could be like this:

If the function is small, 
        save the return status in a variable and return at the end. 
else 
        return immediately.

Answer 5

For this case, I prefer:

boolean validate (DomainObject o) {
    if (o.property == x ||
        o.property2 == y ||
        ...) {
          return true;
    } else {
          return false;
}

In general, I like to use early return to handle error conditions, and return at the end to return computed results.

Answer 6

Personally, I like the second method better. It is straightforward and clearer to me, but I do know there are people who must have only one return in a function.