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;
       }
   }

}