Finding prime numbers with the Sieve of Eratosthenes (Originally: Is there a better way to prepare this array?)

Question

Note: Version 2, below, uses the Sieve of Eratosthenes. There are several answers that helped with what I originally asked. I have chosen the Sieve of Era

Answer 1

Create an ArrayList<Integer> and then convert to an int[] at the end.

There are various 3rd party IntList (etc) classes around, but unless you're really worried about the hit of boxing a few integers, I wouldn't worry about it.

You could use Arrays.copyOf to create the new array though. You might also want to resize by doubling in size each time you need to, and then trim at the end. That would basically be mimicking the ArrayList behaviour.