package listImplementation;

public class MyList {

	// The maximum possible size of a list.
	public static final int MaxSize = 100;

	// The array index of the last element in
	// the list. A value of -1 means the list
	// is currently empty.
	private int tail = -1;

	// The list elements, stored in an array.
	private Object[] store = new Object[MaxSize];

	// Number of all additions (collectively)
	// done to all lists.
	private static int totalNumberOfAdditions = 0;

	// ==========================================================
	// Below are the 3 methods that the students need to define:
	// ==========================================================

	// Add a new element at the start of the list
	// (if there’s space left).
	public void add(Object newItem) {
		if (tail < MaxSize - 1) {
			for (int i = tail; i >= 0; i--) {
				store[i + 1] = store[i];
			}
			store[0] = newItem;
			tail++;
			totalNumberOfAdditions++;
		} else {
			System.out.println("Sorry, list full.");
		}
	}

	// Return the value at the start of the list and remove
	// the element; check that the list has elements in it!
	public Object getValue() {
		Object ans = "";
		if (tail >= 0) {
			ans = store[0];

			for (int count = 1; count <= tail; count++)
				store[count - 1] = store[count];
			tail--;
		} else {
			System.out.println("Sorry, list empty.");
		}
		return ans;
	}

	// Return the value at the "tail" of the list, without
	// removing it; check that the list has elements in it!
	public Object get() {
		Object ans = "";
		if (tail >= 0) {
			ans = store[tail];
		} else {
			System.out.println("Sorry, list empty.");
		}
		return ans;
	}

	// =====================================================
	// Below are some additional methods that you may ask
	// the students to define:
	// =====================================================

	// Return the number of elements that are
	// currently in the list.
	public int size() {
		return tail + 1;
	}

	// Return the total number of additions
	// done to all stacks (collectively).
	public static int getNumberOfAdditions() {
		return totalNumberOfAdditions;
	}

	// Check if the list has no elements in it -- return
	// true if the stack is empty, otherwise return false.
	public boolean isEmpty() {
		if (tail >= 0) {
			return false;
		} else {
			return true;
		}
	}

	// Print the list from top to bottom.
	// (not a standard function of lists!)
	public void print() {
		int i;
		for (i = 0; i <= tail; i++) {
			System.out.println(store[i]);
		}
	}

}