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by vbezhenar
3030 days ago
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But it's a good style: return concrete class, so if I really need those implementation details, I can have them without casts and potential runtime errors. Return as concrete type as possible and declare variable for holding this result as abstract as possible. |
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If I commit to returning an ArrayList then it's not backwards compatible if I want to change to a different concrete List. My experience has been that if you return a concrete class then people will rely on those details even when they don't need to. And if you're writing a library that others depend on then you don't even know how they're using your returned value.
Of course if people are doing unsafe downcasts because they need the guarantees of a particular implementation then you should just return the ArrayList directly. And fortunately this change is backwards compatible, so there's no need to worry!