How are Integer arrays stored internally, in the JVM?

Question

An array of ints in java is stored as a block of 32-bit values in memory. How is an array of Integer objects stored? i.e.

int[] vs. Integer[]

Answer 1

It won't be much slower, but because an Integer[] must accept "null" as an entry and int[] doesn't have to, there will be some amount of bookkeeping involved, even if Integer[] is backed by an int[].

So if every last ounce of performance matters, user int[]