title: Why class Node in LinkedList defined as static but not normal class
body: <p>In package java.util.LinkedList, the Class Node defined as one static class, is it necessary? What is the goal? </p>
  
  <p>We can find source code from this <a href="http://www.docjar.com/html/api/java/util/LinkedList.java.html" rel="noreferrer">page</a>.</p>