hi, i need someone to look at my homework and give me comment where and how should i begain with.
Choose one of the stack implementations and implement a method with this specification:
Object itemAt (int n)
//precondition: 0<=n and n<size()
//postcondition: the return value is the item that is n from the top (with the top at n=0, the next at n=1 and so on). The stack is not changed
Throw a NoSuchElementException if the precondition is violated from (java.util.NoSuchElementException).