STACKS GENERICS

import java.util.ArrayList;

public class Stack<E extends Number> {
    private ArrayList<E> list;

    public Stack(ArrayList<E> list) {
        this.list = list;
    }

    public void push(E element) {
        list.add(element);
    }

    public E pop() {
        if (list.isEmpty()) {
            throw new IllegalStateException("Stack is empty");
        }
        return list.remove(list.size() - 1);
    }

    public int size() {
        return list.size();
    }

    public double average() {
        if (list.isEmpty()) {
            return 0.0;
        }
        double sum = 0.0;
        for (E element : list) {
            sum += element.doubleValue();
        }
        return sum / list.size();
    }

    public boolean compareAverage(Stack<? extends Number> other) {
        return Double.compare(this.average(), other.average()) == 0;
    }

    public static void main(String[] args) {
        Stack<Integer> s1 = new Stack<>(new ArrayList<>());
        s1.push(1);
        s1.push(2);
        s1.push(3);
        s1.push(4);
        s1.push(5);
        System.out.println("Integer stack average: " + s1.average());

        Stack<Double> s2 = new Stack<>(new ArrayList<>());
        s2.push(1.1);
        s2.push(2.2);
        s2.push(3.3);
        s2.push(4.4);
        s2.push(5.5);
        System.out.println("Double stack average: " + s2.average());

        System.out.println("Same average? " + s1.compareAverage(s2));
    }
}