package java.util;
public class LinkedList<E>
 extends AbstractSequentialList<E>
 implements List<E>, Deque<E>, Cloneable, java.io.Serializable{
 transient int size = 0;
 transient Node<E> first;
 transient Node<E> last;
}

 private static class Node<E> {
  E item;
  Node<E> next;
  Node<E> prev;

  Node(Node<E> prev, E element, Node<E> next) {
   this.item = element;
   this.next = next;
   this.prev = prev;
  }
 }

 public E get(int index) {
  checkElementIndex(index);
  return node(index).item;
 }
 public E set(int index, E element) {
  checkElementIndex(index);
  Node<E> x = node(index);
  E oldVal = x.item;
  x.item = element;
  return oldVal;
 }

 Node<E> node(int index) {
  // assert isElementIndex(index);

  if (index < (size >> 1)) {
   Node<E> x = first;
   for (int i = 0; i < index; i++)
    x = x.next;
   return x;
  } else {
   Node<E> x = last;
   for (int i = size - 1; i > index; i--)
    x = x.prev;
   return x;
  }
 }

  List<Integer> list = new LinkedList<>();
  list.add(4);
  list.add(2);
  list.add(3);
  list.add(5);

  for(int i:list)
   System.out.println(i);
  System.out.println(list);

4
2
3
5
[4, 2, 3, 5]

 List<Integer> list = new LinkedList<>();
  list.add(4);
  list.add(2);
  list.add(3);
  list.add(5);
  list.add(7);
  list.add(5);
  list.add(11);
  list.add(14);
  list.add(10);
  list.add(9);
  System.out.println(list);
  List<Integer> list2 = list.subList(3, 6);
  System.out.println(list2);
  list2.set(2, 50);

  System.out.println("============");
  System.out.println(list);
  System.out.println(list2);

[4, 2, 3, 5, 7, 5, 11, 14, 10, 9]
[5, 7, 5]
============
[4, 2, 3, 5, 7, 50, 11, 14, 10, 9]
[5, 7, 50]