LinkedList的特点
非线程安全
支持序列化
双向链表
成员变量
transient int size = 0;
transient Node<E> first; // 指向第一个元素
transient Node<E> last; // 指向最后一个元素
链表结点,三个属性:元素、上一结点、下一结点
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;} }
基本方法
增 add
public boolean add(E e) {linkLast(e);return true; }void linkLast(E e) {final Node<E> lastTmp = last;final Node<E> newNode = new Node<>(lastTmp, e, null);last = newNode;if (lastTmp == null)first = newNode;elselastTmp.next = newNode;size++;modCount++; }
删 remove
removeLast
public E removeLast() {final Node<E> l = last;if (l == null)throw new NoSuchElementException();return unlinkLast(l); }private E unlinkLast(Node<E> l) {// assert l == last && l != null;final E element = l.item;final Node<E> prev = l.prev;l.item = null;l.prev = null; // help GClast = prev;if (prev == null)first = null;elseprev.next = null;size--;modCount++;return element; }
remove
public E remove(int index) {checkElementIndex(index);return unlink(node(index)); }E unlink(Node<E> x) {// assert x != null;final E element = x.item;final Node<E> next = x.next;final Node<E> prev = x.prev;if (prev == null) { // index的结点是头结点first = next;} else {prev.next = next;x.prev = null;}if (next == null) { // index的结点是尾结点last = prev;} else {next.prev = prev;x.next = null;}x.item = null;size--;modCount++;return element; }
改 set
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;} }
查找index位置结点的时候,判断在前半段还是后半段,然后从头结点或者尾结点进行遍历
查 get
public E get(int index) {checkElementIndex(index);return node(index).item; }
扩容原理
增加新结点,将新结点联结进双链表
一些问题
参考
http://blog.csdn.net/ns_code/article/details/35787253