package generics;

/**

* RUN:

* javac generics/LinkedStack.java && java generics.LinkedStack

* OUTPUT:

* stun!

* on

* Phases

*/

public class LinkedStack<T> {

private static class Node<U> {

U item;

Node<U> next;

Node() {

item = null;

next = null;

}

Node(U item, Node<U> next) {

this.item = item;

this.next = next;

}

boolean end() {

return item == null && next == null;

}

}

private Node<T> top = new Node<T>(); // end sentinel !!!

public void push(T item) {

top = new Node<T>(item, top);

}

public T pop() {

T result = top.item;

if (! top.end()) {

top = top.next;

}

return result;

}

public static void main(String[] args) {

LinkedStack<String> lss = new LinkedStack<String>();

for (String s : "Phases on stun!".split(" ")) {

lss.push(s);

}

String s;

while((s = lss.pop()) != null) {

System.out.println(s);

}

}

}