Using Count Element Method To Count Occurrence Of Characters In Array

I have an array with the following characters {'E', 'L','E','P','H','A','N','T','P','O'}

now, I need an array that will store the first array such that only the occurence occurs e.g {'E','L','P','H','A','N','T','O'} Notice that the characters 'E' and 'P' occur twice and as a result were not repeated the second time in the new array.

How would one go about this using the counting elements technique?

I tried this but not sure how to use the counting elements technique.

char [] arr = new char{'E', 'L','E','P','H','A','N','T','P','O'};
char[] bucket = new char[(arr[0] * arr.length)];
for (int i = 0; i < len; i++)
bucket[arr[i]]++;