1.双链表结构
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;public LinkedList() {}
}2.add
创建Node
更新last
更新老last的next
public class LinkedList<E>extends AbstractSequentialList<E>implements List<E>, Deque<E>, Cloneable, java.io.Serializable{public boolean add(E e) {linkLast(e);return true;}void linkLast(E e) {final Node<E> l = last;//创建Node//prev是last，next是nullfinal Node<E> newNode = new Node<>(l, e, null);last = newNode; //更新lastif (l == null){//如果之前没有元素first = newNode; //头也是新元素} else{l.next = newNode;}size++; //更新个数modCount++;}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;}}
}3.get
遍历的方式获得元素
public class LinkedList<E>extends AbstractSequentialList<E>implements List<E>, Deque<E>, Cloneable, java.io.Serializable{public E get(int index) {checkElementIndex(index); //判断index是否为有效范围内的indexreturn node(index).item;}Node<E> node(int index) {// assert isElementIndex(index);if (index < (size >> 1)) {//如果index小于size的一半，从first开始遍历Node<E> x = first;for (int i = 0; i < index; i++){x = x.next;}return x;} else {Node<E> x = last; //不然从尾开始遍历for (int i = size - 1; i > index; i--){x = x.prev;}return x;}}
}4.remove index
先通过遍历的方式获得元素
然后将该元素从列表移除
public class LinkedList<E>extends AbstractSequentialList<E>implements List<E>, Deque<E>, Cloneable, java.io.Serializable{public E remove(int index) {checkElementIndex(index);//node(index)找到index位置的nodereturn unlink(node(index));}//将找到的node从链表移除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) {//表示找到的元素为第一个元素first = next;} else {prev.next = next; //prev node next 移除nodex.prev = null;//把这个元素的prev赋值为null}if (next == null) {//找到的元素为最后一个元素last = prev;} else {next.prev = prev;x.next = null; //把这个元素的next赋值为null}x.item = null; //把这个元素的item赋值为nullsize--;modCount++;return element;}
}5.remove object移除元素
遍历找到元素后，移动该元素
public class LinkedList<E>extends AbstractSequentialList<E>implements List<E>, Deque<E>, Cloneable, java.io.Serializable{public boolean remove(Object o) {if (o == null) {for (Node<E> x = first; x != null; x = x.next) {if (x.item == null) {unlink(x); //移除元素return true;}}} else {for (Node<E> x = first; x != null; x = x.next) {if (o.equals(x.item)) {unlink(x);return true;}}}return false;}
}
)
