Should I avoid using Java Label Statements?

Question

Today I had a coworker suggest I refactor my code to use a label statement to control flow through 2 nested for loops I had created. I've never used them before because personally I think they decrease the readability of a program. I am willing to change my mind about using them if the argument is solid enough however. What are people's opinions on label statements?

Answer 1

Many algorithms are expressed more easily if you can jump across two loops (or a loop containing a switch statement). Don't feel bad about it. On the other hand, it may indicate an overly complex solution. So stand back and look at the problem.

Some people prefer a "single entry, single exit" approach to all loops. That is to say avoiding break (and continue) and early return for loops altogether. This may result in some duplicate code.

What I would strongly avoid doing is introducing auxilary variables. Hiding control-flow within state adds to confusion.

Splitting labeled loops into two methods may well be difficult. Exceptions are probably too heavyweight. Try a single entry, single exit approach.

Answer 2

Labels are like goto's: Use them sparingly, and only when they make your code faster and more importantly, more understandable,

e.g., If you are in big loops six levels deep and you encounter a condition that makes the rest of the loop pointless to complete, there's no sense in having 6 extra trap doors in your condition statements to exit out the loop early.

Labels (and goto's) aren't evil, it's just that sometimes people use them in bad ways. Most of the time we are actually trying to write our code so it is understandable for you and the next programmer who comes along. Making it uber-fast is a secondary concern (be wary of premature optimization).

When Labels (and goto's) are misused they make the code less readable, which causes grief for you and the next developer. The compiler doesn't care.