Example of Stack in Java

package com.concretepage.util;
import java.util.Stack;
public class StackDemo {
    public static void main(String[] args) {
        Stack st = new Stack();
        st.add("A");
        st.add("B");
        st.add("C");
        for(String s : st){
            System.out.println(s);
        }
        //returns current capacity of Stack
        System.out.println(st.capacity());
        //returns true if empty
        System.out.println(st.empty());
        //returns first element
        System.out.println(st.firstElement());
        //returns last element
        System.out.println(st.lastElement());
        //gets the top element but does not remove
        System.out.println(st.peek());
        //pushes the element at the top of element
        System.out.println(st.push("D"));
        //removes the element from the top
        System.out.println(st.pop());
        
    }
}