自己实现链表数据结构　LinkedList

package com.crg.linkedlist;

import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.NoSuchElementException;


/**
 * 实现一个自定义的双链表数据结构的　LinkedList
 * @author crg
 *
 * @param <AnyType>
 */
public class MyLinkedList<AnyType> implements Iterable<AnyType>{

/**
 * 该链表当前的　size
 */
private int mTheSize;

/**
 * 链表被修改的次数的合计，添加节点，删除节点的总数
 */
private int mModCount;

/**
 * 链表的头，空节点
 */
private Node<AnyType> mBeginMarker;

/**
 * 　链表的尾，空节点
 */
private Node<AnyType> mEndMarker;

/**
 * 一个嵌套类，链表的每一个节点都是该类的一个对象
 * @author crg
 *
 * @param <AnyType>
 */
private static class Node<AnyType>{
        public AnyType mData;
        public Node<AnyType> mPrev;
        public Node<AnyType> mNext;
        public Node(AnyType data, Node<AnyType> prev, Node<AnyType> next){
            mData = data;
            mPrev = prev;
            mNext = next;
        }
    }

/**
 * 构造一个空链表
 */
    public MyLinkedList(){
        clear();
    }

/**
 * 置空链表
 */
    public void clear(){
        mBeginMarker = new Node<AnyType>(null, null, null);
        mEndMarker = new Node<AnyType>(null, mBeginMarker, null);
        mBeginMarker.mNext = mEndMarker;
        mTheSize = 0;
        mModCount ++;
    }

/**
 * 获得当前链表节点的数量
 * @return
 */
    public int size(){
return mTheSize;
    }

    public boolean isEmpty(){
return mTheSize == 0;
    }




/**
 * 在　p 节点的前面添加一个　数据为　data　的节点
 * @param p
 * @param data
 */
private void addBefore(Node<AnyType> p, AnyType data){
        Node<AnyType> newNode = new Node<AnyType>(data, p.mPrev, p);
        newNode.mPrev.mNext = newNode;
        p.mPrev = newNode;
        mTheSize ++;
        mModCount ++;
    }

/**
 * 在链表末尾添加　一个 AnyType
 * @param x
 */
    public void add(AnyType x){
        add(size(), x);
    }

/**
 * 在链表指定位置添加　一个 AnyType
 * @param idx
 * @param x
 */
    public void add(int idx, AnyType x){
        addBefore(getNode(idx), x);
    }

/**
 * 获得　idx 对应的节点
 * @param idx
 * @return
 */
private Node<AnyType> getNode(int idx){
        Node<AnyType> result;
if (idx < 0 || idx > size()) {
throw new IndexOutOfBoundsException();
        }

if (idx < size()/2) {
            result = mBeginMarker.mNext;
for (int i = 0; i < idx; i++) {
                result = result.mNext;
            }
        } else {
            result = mEndMarker;
for (int i = size(); i > idx; i--) {
                result = result.mPrev;
            }
        }

return result;
    }

/**
 * 替换某个节点的值
 * @param idx
 * @param newVal
 * @return
 */
    public AnyType set(int idx, AnyType newVal){
        Node<AnyType> oldNode = getNode(idx);
        AnyType oldVal = oldNode.mData;
        oldNode.mData = newVal;
return oldVal;
    }

/**
 * 移除指定位置的　数据
 * @param idx
 * @return
 */
    public AnyType remove(int idx){
return remove(getNode(idx));
    }

/**
 * 移除一个指定的节点　p
 * @param p
 * @return
 */
private AnyType remove(Node<AnyType> p){
        p.mPrev.mNext = p.mNext;
        p.mNext.mPrev = p.mPrev;
        mTheSize --;
        mModCount --;
return p.mData;
    }
@Override
    public Iterator<AnyType> iterator() {
return new LinkedListIterator();
    }

private class LinkedListIterator implements Iterator<AnyType>{
private Node<AnyType> current = mBeginMarker.mNext;
private int expectedModCount = mModCount;
private boolean okToRemove = false;

@Override
        public boolean hasNext() {
return current != mEndMarker;
        }

@Override
        public AnyType next() {
if (expectedModCount != mModCount) {
throw new ConcurrentModificationException();
            }
if (!hasNext()) {
throw new NoSuchElementException();
            }
            AnyType nextItem = current.mData;
            current = current.mNext;
            okToRemove = true;
return nextItem;
        }

@Override
        public void remove() {
if (expectedModCount != mModCount) {
throw new ConcurrentModificationException();
            }

if (!okToRemove) {
throw new IllegalStateException();
            }
            MyLinkedList.this.remove(current.mPrev);
            okToRemove = false;
            expectedModCount --;
        }
    }
}

源码参考：
https://github.com/aloe-all/MyLinkedList.git