Array Stack

package DataS;

public class Array_Stack {
    
    static class ArrayStack {
        private int[] stack;
        private int size;
        private int capacity;

        public ArrayStack(int initialCapacity) {
            stack = new int[initialCapacity];
            capacity = initialCapacity;
            size = 0;
        }

        public void push(int x) {
            if (size == capacity) {
                resize();
            }
            stack[size++] = x;
        }

        public int pop() {
            if (isEmpty()) {
                throw new RuntimeException("Stack is empty");
            }
            int poppedElement = stack[--size];
            return poppedElement;
        }

        public int top() {
            if (isEmpty()) {
                throw new RuntimeException("Stack is empty");
            }
            return stack[size - 1];
        }

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

        private void resize() {
            int newCapacity = 2 * capacity;
            int[] newStack = new int[newCapacity];
            System.arraycopy(stack, 0, newStack, 0, capacity);
            capacity = newCapacity;
            stack = newStack;
        }
    }

    public static void main(String[] args) {
        ArrayStack stack = new ArrayStack(2);

        stack.push(5);
        stack.push(12);
        stack.push(20);

        System.out.println("Top element: " + stack.top());
        System.out.println("Popped element: " + stack.pop());
        System.out.println("Top element after pop: " + stack.top());
        System.out.println("Is stack empty? " + stack.isEmpty());

        stack.pop();
        stack.pop();

        System.out.println("Is stack empty after popping all elements? " + stack.isEmpty());
    }
}