public class GenericStack<T>
{
    private T[] items;
    private int top;    // Index of the next place to put a T object

    public GenericStack(int size)
    {
        items = (T[]) new Object[size];
        top = 0;
    }

    public boolean isEmpty()
    {
        return (top == 0);
    }

    public boolean isFull()
    {
        return (top == items.length);
    }

    public boolean push(T item)
    {
        if(isFull())
        {
            // No place to put the object
            return false;
        }
        else
        {
            // Add the object to the next open slot
            items[top] = item;
            top += 1;
            return true;
        }
    }

    public T pop()
    {
        if(isEmpty())
        {
            // Nothing to pop
            return null;
        }
        else
        {
            // Return the item at the top of the stack
            top -= 1;
            return items[top];
        }
    }
    
    public void displayState()
    {
        System.out.println("####");
        for(int i = top - 1; i >= 0; --i)
        {
            System.out.println(items[i]);
        }
    }
}