How to generate random array of ints using Stream API Java 8?

Question

I am trying to generate random array of integers using new Stream API in Java 8. But I haven\'t understood this API clearly yet. So I need help. Here is my code.

Answer 1

To generate random numbers from range 0 to 350, limiting the result to 10, and collect as a List. Later it could be typecasted.

However, There are no guarantees on the type, mutability, serializability, or thread-safety of the List returned.

List<Object> numbers =  new Random().ints(0,350).limit(10).boxed().collect(Collectors.toList());

and to get thearray of int use

int[] numbers =  new Random().ints(0,350).limit(10).toArray();

Answer 2

You can do it using ThreadLocalRandom.

int[] randInts = ThreadLocalRandom.current().ints().limit(100).toArray();

Answer 3

There's no reason to boxed(). Just receive the Stream as an int[].

int[] array = intStream.limit(limit).toArray();

Answer 4

If you want primitive int values, do not call IntStream::boxed as that produces Integer objects by boxing.

Simply use Random::ints which returns an IntStream:

int[] array = new Random().ints(size, lowBound, highBound).toArray();