package com;
import java.util.NoSuchElementException;
public class MyLinkedList implements MyList {
int size = 0;
Node first;
Node last;
private static class Node {
Object item;
Node next;// ָ����һ���ڵ�
Node prev;// ָ����һ���ڵ�
Node(Node prev, Object element, Node next) {
this.item = element;
this.next = next;
this.prev = prev;
}
}
public boolean add(Object o) {
linkLast(o);
return true;
}
/**
* ��Ԫ�ز���ָ���±�
*
* @Author xuyangyang
* @Describe
* @date 2017��2��21��
* @param index
* @param o
*/
public void add(int index, Object o) {
checkPositionIndex(index);
if (index == size) {
linkLast(0);
} else {
LinkBefore(o, node(index));
}
}
public void addFirst(Object o) {
linkFirst(o);
}
public void addLast(Object o) {
linkLast(o);
}
private void linkFirst(Object o) {
final Node f = first;
final Node newNode = new Node(null, o, f);
first = newNode;
if (first == null) {
first = newNode;
} else {
f.prev = newNode;
}
size++;
}
void LinkBefore(Object o, Node succ) {
final Node pred = succ.prev;
final Node newNode = new Node(pred, o, succ);// �Ȱ��½��ڵ��ǰ��ָ�븳ֵ
succ.prev = newNode;// �Ѳ���ĺ�һ���ڵ��ǰָ��ָ���½ڵ�
if (pred == null) {
first = newNode;// �������ڵ�ǰָ��Ϊ��,��Ϊͷָ��
} else {
pred.next = newNode;// ��ǰһ���ڵ�ĺ�ָ��ָ���½ڵ�;
}
size++;
}
/**
* ����ָ�뷵�ؽڵ���Ϣ
*
* @Author xuyangyang
* @Describe
* @date 2017��2��21��
* @param index
* @return
*/
Node node(int index) {
if (index < (size >> 1)) {// ����ڵ�������ǰ�벿��,
Node x = first;// ��ͷָ���x;
for (int i = 0; i < index; i++)
// ����ǰ�벿�ֽڵ�,
x = x.next;// Ѱ������index��ǰһ���ڵ�,����nextָ��
return x;
} else {
Node x = last;
for (int i = size - 1; i > index; i--)
x = x.prev;
return x;
}
}
/**
* �������
*
* @Author xuyangyang
* @Describe
* @date 2017��2��21��
* @param o
*/
private void linkLast(Object o) {
final Node l = last;
final Node newNode = new Node(l, o, null);
last = newNode;
if (last == null) {
first = newNode;
} else {
l.next = newNode;
}
size++;
}
public Object get(int index) {
checkElementIndex(index);
return node(index).item;
}
/**
* ���Ԫ���Ǽ��
*
* @Author xuyangyang
* @Describe
* @date 2017��2��21��
* @param index
*/
private void checkElementIndex(int index) {
if (index >= 0 && index < size) {
} else {
throw new IndexOutOfBoundsException();
}
}
/**
* ���Ԫ��ʱ���ָ��
*
* @Author xuyangyang
* @Describe
* @date 2017��2��21��
* @param index
*/
private void checkPositionIndex(int index) {
if (index >= 0 && index <= size)
throw new IndexOutOfBoundsException();
}
public boolean reomve(Object o) {
if (o == null) {
for (Node x = first; x != null; x = x.next) {
if (x.item == null) {
unlink(x);
return true;
}
}
} else {
for (Node x = first; x != null; x = x.next) {
if (o.equals(x.item)) {
unlink(x);
return true;
}
}
}
return false;
}
@Override
public Object remove(int index) {
checkElementIndex(index);
return unlink(node(index));
}
private Object unlink(Node x) {
final Object element = x.item;
final Node next = x.next;
final Node prev = x.prev;
if (prev == null) {
first = next;
} else {
prev.next = next;
x.prev = null;
}
if (next == null) {
last = prev;
} else {
next.prev = prev;
x.next = null;
}
x.item = null;
size--;
return element;
}
public Object removeFirst() {
final Node f = first;
if (f == null) {
throw new NoSuchElementException();
}
return unlinkFirst(f);
}
private Object unlinkFirst(Node f) {
final Object element = f.item;
final Node next = f.next;
f.item = null;
f.next = null;
first = next;
if (next == null) {
last = null;
} else {
next.prev = null;
}
size--;
return element;
}
public Object removeLast() {
Node l = last;
if (l == null) {
throw new NoSuchElementException();
}
return unLinkLast(l);
}
private Object unLinkLast(Node l) {
final Object element = l.item;
final Node prev = l.prev;
last = prev;
l.item = null;
l.prev = null;
if (prev == null) {
first = null;
} else {
prev.next = null;
}
size--;
return element;
}
public int size() {
return size;
}
}