Библиотека программиста

public
class Central {
 public
  static void main(String args[]) {
    LinkedList linkedList = new LinkedList();
    LinkedList.Node head = linkedList.head();
    linkedList.add(new LinkedList.Node("1"));
    linkedList.add(new LinkedList.Node("2"));
    linkedList.add(new LinkedList.Node("3"));
    linkedList.add(new LinkedList.Node("4"));
    linkedList.add(new LinkedList.Node("5"));
    linkedList.add(new LinkedList.Node("6"));
    linkedList.add(new LinkedList.Node("7"));
    linkedList.add(new LinkedList.Node("8"));
    linkedList.add(new LinkedList.Node("9"));
    linkedList.add(new LinkedList.Node("10"));
    LinkedList.Node current = head;
    int length = 0;
    LinkedList.Node middle = head;
    while (current.next() != null) {
      length++;
      if (length % 2 == 0) {
        middle = middle.next();
      }
      current = current.next();
    }
    if (length % 2 == 1) {
      middle = middle.next();
    }
    System.out.println("length of LinkedList: " + length);
    System.out.println("middle element of LinkedList : " + middle);
  }
} 

class LinkedList {
 private
  Node head;
 private
  Node tail;
 public
  LinkedList() {
    this.head = new Node("head");
    tail = head;
  }
 public
  Node head() { return head; }
 public
  void add(Node node) {
    tail.next = node;
    tail = node;
  }
 public
  static class Node {
   private
    Node next;
   private
    String data;
   public
    Node(String data) { this.data = data; }
   public
    String data() { return data; }
   public
    void setData(String data) { this.data = data; }
   public
    Node next() { return next; }
   public
    void setNext(Node next) { this.next = next; }
   public
    String toString() { return this.data; }
  }
}