Array /Stream API problem

Question

I'm trying to print the numbers of an array to the second power in one row separated by single whitespaces using stream API like this:

int[] arr = {5, 3, 1};
Arrays.stream(arr)
.map(x -> (int)Math.pow(x, 2))
.map(x -> x + " ")
.forEach(System.out::print);

In this row --> .map(x -> x + " ") i get an exception ( Exception in thread "main" java.lang.Error: Unresolved compilation problem:
Type mismatch: cannot convert from String to int )

The strange thing if I try the same this using this method but on an ArrayList it is working fine:

List<Integer> nums = new ArrayList<Integer>();
nums.add(3);
nums.add(2);
nums.stream()
.map(x -> (int)Math.pow(x, 2))
.map(x -> x + " ")
.forEach(System.out::print);

If anyone could help me I would really appreciate it :)

Answer 1

Try mapToObj instead, it will an returns an object-valued stream.

This works fine:

int[] arr = {5, 3, 1};
Arrays.stream(arr)
.map(x -> (int)Math.pow(x, 2))
.mapToObj(x -> x + " ")
.forEach(System.out::print);

I think this code runs because Integer is a wrapper not primitive type.
List<Integer> nums = new ArrayList<Integer>();
nums.add(3);
nums.add(2);
nums.stream()
.map(x -> (int)Math.pow(x, 2))
.map(x -> x + " ")
.forEach(System.out::print);

Answer 2

0_O-[Mägár_Sám_Äkà_Nüllpøïntêr_Èxëcéptïön]~~

Thanks, you solution works :) I also checked your explanation, and it seems to be true, this code is also running fine:
Integer[] array = {3, 2, 5};
Arrays.stream(array)
.map(x -> (int)Math.pow(x, 2))
.map(x -> x + " ")
.forEach(System.out::print);