As soon as you start protecting yourself from the dangers of the unidentified dumbfool programmer, you get exactly this. In that case you can't do pretty much a

As soon as you start protecting yourself from the dangers of the unidentified dumbfool programmer, you get exactly this. In that case you can't do pretty much anything without wrapping it around read only collections or iterators or accessors first, whereas what you really want is just to return a list of damn things. Java seems to be the breeding pit for such practices: it's a supposedly secure virtual machine that allows you to hide stuff so deep in your rear end that you can barely access it yourself any longer without a delicate assessment of numerous design patterns. That sort of capability allows you to get on that encapsulation-road far enough that it might not be feasible to ever back down and rewrite things in a sensible way. But the truth is, all you need is the array holding the important values and all you need to do is document the function appropriately. "Don't modify the returned list" would be a good start. Then you want your developers have the skills to understand each part of that sentence. On the other hand, if someone won't it's not your problem since you documented the behaviour. Some languages, such as C, allow you to tell that more explicitly with the 'const' keyword and even have the compiler act as a gatekeeper. The developer can still write the returned value into a non-const variable and mess around with that but he's already broken the contract by that time. In Java, it should be more than sufficient to cast it into a type denoting a read-only array or collection but I don't see a common, real reason to not eventually return that single array.