LinkedList源码分析

一、属性及获取属性：1、sizetransient int size = 0;/** * Pointer to first node. * Invariant: (first == null && last == null) || * (first.prev == null && first.item != null) /transient Node<E> first;/* * Pointer to last node. * Invariant: (first == null && last == null) || * (last.next == null && last.item != null) /transient Node<E> last;获取public int size() { return size;}二、构造函数//Constructs an empty listpublic LinkedList() {}public LinkedList(Collection<? extends E> c) { this(); addAll(c);}三、类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; }}四、方法1、NodeNode<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; }}、linkFirst/** * Links e as first element. /private void linkFirst(E e) { final Node<E> f = first; final Node<E> newNode = new Node<>(null, e, f); first = newNode; if (f == null) last = newNode; else f.prev = newNode; size++; modCount++;}void linkLast(E e) { final Node<E> l = last; final Node<E> newNode = new Node<>(l, e, null); last = newNode; if (l == null) first = newNode; else l.next = newNode; size++; modCount++;}、add、addFirstpublic void addFirst(E e) { linkFirst(e);}public boolean add(E e) { linkLast(e); return true;}linkLast2、setpublic E set(int index, E element) { checkElementIndex(index); Node<E> x = node(index); E oldVal = x.item; x.item = element; return oldVal;}3、getpublic E get(int index) { checkElementIndex(index); return node(index).item;}、clearpublic void clear() { // Clearing all of the links between nodes is “unnecessary”, but: // - helps a generational GC if the discarded nodes inhabit // more than one generation // - is sure to free memory even if there is a reachable Iterator for (Node<E> x = first; x != null; ) { Node<E> next = x.next; x.item = null; x.next = null; x.prev = null; x = next; } first = last = null; size = 0; modCount++;}、Push Poppublic void push(E e) { addFirst(e);}public E pop() { return removeFirst();}*、node(int index)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; }}