stack-arraylist-to-stack.java

import java.util.ArrayList;

public class Main{
    
    static class stack{
        
        static ArrayList<Integer> list = new ArrayList<>();
        
        
        public static boolean isEmpty(){
            return list.size() == 0;
        }
        
        //push
        public static void push(int data){
            list.add(data);
        }
        
        //pop
        public static int pop(){
            
            if(isEmpty()){
                return -1;   // stack is empty
                
            }
            int top = list.get(list.size()-1);
            list.remove(list.size()-1);
            return top;
        }
        
        //peek
        public static int peek(){
             return list.get(list.size()-1);
        }
    
    }
    
    
    public static void main(String[]args){
        
        stack s = new stack();
        s.push(1);
        s.push(2);
        s.push(3);
        
        while(!s.isEmpty()){
            System.out.println(s.peek());
            s.pop();
        }
        
        
    }
}