// generics/LinkedStack.java
// (c)2021 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// A stack implemented with an internal linked structure
public class LinkedStack {
private static class Node {
U item;
Node next;
Node() { item = null; next = null; }
Node(U item, Node next) {
this.item = item;
this.next = next;
}
boolean end() {
return item == null && next == null;
}
}
private Node top = new Node<>(); // End sentinel
public void push(T item) {
top = new Node<>(item, top);
}
public T pop() {
T result = top.item;
if(!top.end())
top = top.next;
return result;
}
public static void main(String[] args) {
LinkedStack lss = new LinkedStack<>();
for(String s : "Phasers on stun!".split(" "))
lss.push(s);
String s;
while((s = lss.pop()) != null)
System.out.println(s);
}
}
/* Output:
stun!
on
Phasers
*/