Explanation/Reference:
Explanation:
push
void push(E e)
Pushes an element onto the stack represented by this deque (in other words, at the head of this deque) if it
is possible to do so immediately without violating capacity restrictions, returning true upon success and
throwing an IllegalStateException if no space is currently available.
This method is equivalent to addFirst(E).
pop
E pop()
Pops an element from the stack represented by this deque. In other words, removes and returns the first
element of this deque.
This method is equivalent to removeFirst().
Returns:
the element at the front of this deque (which is the top of the stack represented by this deque)
Throws:
NoSuchElementException - if this deque is empty