Who knows the easiest way to convert a List of strings to an ArrayList?
I tried setting (ArrayList) before the code but this doesn't do anything.
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2 Answers
Sure:
ArrayList arrayList = new ArrayList(list);
That works because List<T> implements ICollection.
However, I'd strongly advise you to avoid ArrayList (and other non-generic collections) if at all possible. Can you refactor whatever code wants an ArrayList to use a generic collection instead?
10 Comments
AJW
I have a similar use case...can you please explain why you recommend avoid ArrayList and other non-generic collections?
Jon Skeet
@AJW: Because they aren't safe at compile-time - they don't stop you from putting the "wrong" kind of thing in (compared with what you expect) and you need to cast everything coming out of them.
AJW
I understand. Almost every tutorial and codelabs that I've reviewed dealing with a RecyclerView list and its adapter show the use of an ArrayList. Yet the Room database DAOs seem to use List exclusively to return data from for example a SQLite database. So your recommendation would be to use a List in the RecyclerView and its adapter, since the DAO is returning a List?
Jon Skeet
@AJW: I've never even heard of
RecyclerView before that comment (that I remember, anyway) I'm afraid.Jon Skeet
@AJW: If this is Android, bear in mind that there's a big difference between
ArrayList in Java (which is generic) and ArrayList in .NET (which isn't). |
ArrayList has a constructor which accepts an ICollection. Since List<T> implements ICollection, the following should work:
var myArrayList = new ArrayList(myList);
