package task1.basic;
import java.util.ConcurrentModificationException;
import java.util.NoSuchElementException;
import java.util.Objects;
/**
* Created by wanc on 2017/2/21.
* 实现单向链表集合
*/
public class WLinkedList implements WList {
/**
* 首节点
*/
private Node head;
/**
* 计数
*/
private int size = 0;
/**
* 检查是否越界 利用jdk源码的检测方法
*/
private boolean isElementIndex(int index) {
return index >= 0 && index < size;
}
/**
* JDK 源码检测方法
*
* @param index
* @return
*/
private boolean isPositionIndex(int index) {
return index >= 0 && index <= size;
}
/**
* JDK 源码 错误信息
*
* @param index
* @return
*/
private String outOfBoundsMsg(int index) {
return "Index: " + index + ", Size: " + size;
}
/**
* JDK 源码检测方法
*
* @param index
* @return
*/
private void checkElementIndex(int index) {
if (!isElementIndex(index))
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}
/**
* JDK 源码检测方法
*
* @param index
* @return
*/
private void checkPositionIndex(int index) {
if (!isPositionIndex(index))
throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
}
/**
* 获取对应下标的节点
*/
Node node(int index) {
Node x = head;
for (int i = 0; i < index; i++)
x = x.next;
return x;
}
/**
* 在末尾添加数据
*
* @param o
*/
public void add(Object o) {
if (head == null)
head = new Node(o, null);
else {
final Node lastNode = node(size - 1);
final Node newNode = new Node(o, null);
lastNode.next = newNode;
}
size++;
}
/**
* 指定位置添加数据
*
* @param index
* @param o
*/
public void add(int index, Object o) {
checkPositionIndex(index);
if (size == index)
add(o);
else {
final Node prevNode = node(index - 1);
final Node nextNode = prevNode.next;
final Node newNode = new Node(o, nextNode);
prevNode.next = newNode;
size++;
}
}
/**
* 获取指定索引数据
*
* @param index
* @return
*/
public Object get(int index) {
return node(index).data;
}
/**
* 移除指定索引数据
*
* @param index
* @return
*/
public Object remove(int index) {
checkElementIndex(index);
final Node prevNode = node(index - 1);
final Node x = prevNode.next;
if (index - 1 < 0) {
prevNode.next = null;
head = x;
} else {
final Node nextNode = x.next;
prevNode.next = nextNode;
x.next = null;
}
size--;
return x.data;
}
public Object remove(Object element){
Node x=head;
for (int i=0;i<size;i++){
if (Objects.equals(x.data,element))
x=x.next;
}
return null;
}
/**
* 返回数量
*
* @return
*/
public int size() {
return size;
}
/**
* 在链首添加数据
*
* @return
*/
public void addFirst(Object o) {
final Node h = head;
final Node newNode = new Node(o, h);
head = newNode;
size++;
}
/**
* 在链尾添加数据
*
* @return
*/
public void addLast(Object o) {
add(o);
}
/**
* 移除链首数据
*
* @return
*/
public Object removeFirst() {
final Node h = head;
if (h == null)
throw new NoSuchElementException();
final Node newFirst = h.next;
h.next = null;
head = newFirst;
size--;
return h.data;
}
/**
* 移除链尾数据
*
* @return
*/
public Object removeLast() {
final Node prev = node(size - 1 - 1);
final Node l = prev.next;
prev.next = null;
l.next = null;
size--;
return l.data;
}
/**
* 获取迭代器
*
* @return
*/
public WIterator iterator() {
return new LinkedItr();
}
public ListWIterator listIterator() {
return new LinkedItr();
}
/**
* 迭代器实现内部类
*
* @return
*/
private class LinkedItr implements ListWIterator {
int cursor = 0;//游标
int delCursor = -1;
@Override
public boolean hasNext() {
return cursor != size;
}
@Override
public Object next() {
int i = cursor;
if (i > (size - 1)) throw new NoSuchElementException();
Node current = node(i);
if (current == null) throw new IndexOutOfBoundsException();
delCursor = i;
cursor = i + 1;
// System.out.println("i="+i+"-"+current.data);
return current.data;
}
@Override
public void remove() {
if (delCursor < 0) {
throw new IllegalStateException();
}
try {
WLinkedList.this.remove(delCursor);
if (cursor > 0)
cursor--;
delCursor = -1;
} catch (IndexOutOfBoundsException e) {
throw new ConcurrentModificationException();
}
}
}
/**
* 节点内部类 用于保存数据
*/
private static class Node {
Object data;
Node next;
Node(Object data, Node next) {
this.data = data;
this.next = next;
}
}
/**
* 重写toString 方便打印
*
* @return
*/
@Override
public String toString() {
String result = "[";
for (int i = 0; i < size; i++) {
Node n = node(i);
if (i == 0)
result += n.data;
else
result += "," + n.data;
}
return result + "]";
}
/**
* 把该链表逆置
* 例如链表为 3->7->10 , 逆置后变为 10->7->3
*/
public void reverse() {
if (head == null) return;
Node[] nodes = new Node[size];
Node x = head;
for (int i = 0; i < size; i++) {
nodes[i] = x;
x = x.next;
}
head = nodes[nodes.length - 1];
Node tmp = head;
for (int j = nodes.length - 2; j >= 0; j--) {
Node c = nodes[j];
tmp.next = c;
tmp = c;
}
}
/**
* 删除一个单链表的前半部分
* 例如：list = 2->5->7->8 , 删除以后的值为 7->8
* 如果list = 2->5->7->8->10 ,删除以后的值为7,8,10
*/
public void removeFirstHalf() {
int len = size / 2;
remove(0, len);
}
/**
* 从第i个元素开始， 删除length 个元素 ， 注意i从0开始
*
* @param i
* @param length
*/
public void remove(int i, int length) {
checkElementIndex(i);
checkElementIndex(i + length - 1);
if (0 == length) return;
int a = i - 1;
Node p = node(a);//前一个
Node f = p.next;//删除第一个
Node l = node(i + length - 1);//删除最后一个
Node h = l.next;//后一个
//去掉引用 等待GC回收
Node tmp = f;
while (tmp != l) {
Node n = tmp.next;
tmp.next = null;
tmp = n;
}
l.next = null;
if (0 == i)
head = h;
else
p.next = h;
size -= length;
}
/**
* 假定当前链表和list均包含已升序排列的整数
* 从当前链表中取出那些list所指定的元素
* 例如当前链表 = 11->101->201->301->401->501->601->701
* listB = 1->3->4->6
* 返回的结果应该是[101,301,401,601]
*
* @param list
*/
public int[] getElements(WLinkedList list) {
if (list == null) return null;
int[] arr = new int[list.size];
WIterator itr = list.iterator();
int i = 0;
while (itr.hasNext()) {
arr[i] = (int) node((int) itr.next()).data;
i++;
}
return arr;
}
interface ListWIterator extends WIterator {
void remove();
}
/**
* 已知链表中的元素以值递增有序排列，并以单链表作存储结构。
* 从当前链表中中删除在list中出现的元素
*
* @param list
*/
public void subtract(WLinkedList list) {
if (list != null && list.size > 0) {
WIterator itr = list.iterator();
while (itr.hasNext()) {
ListWIterator sourItr = listIterator();
Object value = itr.next();
while (sourItr.hasNext()) {
Object souValue = sourItr.next();
// System.out.println(value+"-"+souValue);
if (value.equals(souValue)) {
// System.out.println(value+"-"+sourItr.next());
sourItr.remove();
// System.out.println("remove");
}
}
// System.out.println("---------------------------------");
}
}
}
}