Get number of duplicates from ArrayList

Question

For example, say I have an ArrayList that could contain the following values:

x
x
x
y
y

Now what I want to retrieve is the number

Answer 1

Well, for this what you can do is to traverse the list from the end. Keep a counter and keep checking for the change in the object. As soon as you detect a change, replace the number in the counter with the current position + 1. Do this till you reach the first position.