How to convert List to int[] in Java?


Unfortunately, I don’t believe there really is a better way of doing this due to the nature of Java’s handling of primitive types, boxing, arrays and generics. In particular:

  • List<T>.toArray won’t work because there’s no conversion from Integer to int
  • You can’t use int as a type argument for generics, so it would have to be an int-specific method (or one which used reflection to do nasty trickery).

I believe there are libraries which have autogenerated versions of this kind of method for all the primitive types (i.e. there’s a template which is copied for each type). It’s ugly, but that’s the way it is I’m afraid 🙁

Even though the Arrays class came out before generics arrived in Java, it would still have to include all the horrible overloads if it were introduced today (assuming you want to use primitive arrays).

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