If-Else statements vs Exception-Catcher?

Question

I got tired of adding seemingly endless if-else statements into my code, so I wondered if it would be better practice if I'd just catch Exceptions if something wasn't right. Eg. instead of saying:

public static boolean firstStringOfArrayIsTheSameAsTheWord(String word, String[] array) { if(word != null) { if(array.length > 0) { return word.equalsIgnoreCase(array[0]); } } return false; }

I'd just have:

public static boolean firstStringOfArrayIsTheSameAsTheWord(String word, String[] array) { try { return word.equals(array[0]); } catch(/*NullPointerException or an ArrayIndexOutOfBoundsException*/ Exception e) { return false; } }

Note that I do know that I could use multiple arguments in the if-statements, but I'm just interested in what method would be better-to-use in practice and why.

Thanks in advance!

You're apt to start another religious war (except that the last one is still on-going). But another "cheater" way to handle it is to put everything in a do { ... } while(false) block and then use break statements to leave the block. — Hot Licks
– Hot Licks, Commented May 17, 2013 at 0:14
One way to make methods like this more readable (less ugly) is to do one if at a time and return immediately if your condition is not met. If you keep your methods simple enough you shouldn't run into a situation where your if/else ladder seems "endless". — jahroy
– jahroy, Commented May 17, 2013 at 0:16
@jahroy That seems like a wonderful solution, thanks a lot! I'll use that in the future. — felix fritz
– felix fritz, Commented May 17, 2013 at 0:38

Community · Accepted Answer · 2017-05-23 11:44:06Z

No, thats not a good idea, thats an abuse of Exception handling.

You are meant to avoid unnecesary exception catching, exceptions should only be used for things that go wrong because they are outside of your control and not as part of the normal program flow. Also, as @SJuan76 said you'll be hiding situations where there is a real Exception.

If you are tired of using if-else statements, you can try using a switch(which will even work for strings in Java 7) or improve polymorphism in your application.

greedybuddha · Accepted Answer · 2013-05-17 00:08:37Z

The general rule is, "use exceptions for exceptional events, never for control flow".

So use the if(...) else ... please.

SJuan76 · Accepted Answer · 2013-05-17 00:12:33Z

First, IIRC correctly exception handling is slow. Not terribly slow, but nothing that you want to use in the mainstream logic.

Second, by working that way, you will be hiding the situations where there is a real Exception. Your user will try to load a file, but will only find that the file was not loaded, would not get any idea if the file was not found, the data was corrupt, whatever. You lose a lot of information.

If you want to make your code simpler, it would be better to do something like

/** * .... * @param word String must not be null. * @param array String[] must not be null, have length at least 1, an array[0] must not be null */ public static boolean firstStringOfArrayIsTheSameAsTheWord(String word, String[] array) { return word.equals(array[0]); }

At least you delegate the responsability for sanitizing the parameters to the code that uses your method. Not a sensible thing to do (it goes against defensive programming) and your coworker will hate working with your code, but better than your first approach.

So besides that it's slow, it's probably also not a good idea to catch multiple exceptions, just in case there's something else is going on, eg. } catch(NullPointerException e) { } catch(ArrayIndexOutOfBoundsException e) { } catch(Exception e) { //Okay, now something went really wrong }, right?
You could do something like that and it would be 'correct', but would not save you any typing, would be slower, and your code would be more difficult to read.

Hot Licks · Accepted Answer · 2013-05-17 00:16:48Z

0

do { if (conditionA) { something; } else { break; } if (conditionB) { somethingElse; } else { break; } ... } while(false);

answered May 17, 2013 at 0:16

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2 Comments

felix fritz Over a year ago

Oh wow, I've never thought about those statements. So what's your opinion? Does the do-while loop make if-statements faster or is it against every programmer's religion? :D

Hot Licks Over a year ago

It's probably fairly cheap, and a good optimizer won't be choked by it. Confusing to the uninitiated, and some pitfalls since it's basically using GOTOs (which, as we all know, are considered harmful).

Luke Tong · Accepted Answer · 2013-05-17 01:01:33Z

The exception approach is not a good idea. Throwing an exception 1. it is slow 2. makes your application unreadable. As @greedybuddha said "use exceptions for exceptional events, never for control flow".

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