Stack

{Task}

Java

public class Stack {

   private Node first = null;
   public boolean isEmpty {
       return (first == null);
   }
   public Object Pop() {
       if (first == null) 
           throw new Exception("Can't Pop from an empty Stack.");
       else {
           Object temp = first.Value;
           first = first.Next;
           return temp;
       }
   }
   public void Push(Object o) {
       first = new Node(o, first);
   }
   class Node {
       public Node Next;
       public Object Value;
       public Node(Object value) {
           this(value, null); 
       }
       public Node(Object value, Node next) {
           Next = next;
           Value = value;
       }
   }

}

C#

 public class Stack
 {
     private Node first = null;
     public bool Empty {
         get {
             return (first == null);
         }
     }
     public object Pop() {
         if (first == null) 
             throw new Exception("Can't Pop from an empty Stack.");
         else {
             object temp = first.Value;
             first = first.Next;
             return temp;
         }
     }
     public void Push(object o) {
         first = new Node(o, first);
     }
     class Node
     {
         public Node Next;
         public object Value;
         public Node(object value): this(value, null) {}
         public Node(object value, Node next) {
             Next = next;
             Value = value;
         }
     }
 }