自己實現了一個LinkedList對照源碼一看，呵呵呵

閒來無事，想聯繫一下對鏈表的操作，上一次寫鏈表還是用C++呢，都已經是兩年前的事情了，現在想用Java試一下，於是自己引入List接口，come on !

寫完以後（沒有關於迭代器的部分），對照源碼看了一下，我去，差距有點大

public class MyLinkedList<E> implements List<E>{
	
	private Node<E> header = null ;
	
	private Node<E> tail = null ;
	
	private int size = 0 ;

	public int size() {
		return size ;
	}

	public boolean isEmpty() {
		return header == null;
	}

	public boolean contains(Object o) {
		return (indexOf(o) == -1);
	}

	public Iterator<E> iterator() {
		// TODO Auto-generated method stub
		return null;
	}

	public Object[] toArray() {
		Object[] objs = new Object[size];
		int count = 0 ;
		for (Node<E> i = header; i != null; i = i.next) {
			objs[count] = i.item ;
		}
		return objs;
	}
    /**
     * 返回指定類型的數組
     */
	@SuppressWarnings("unchecked")
	public <T> T[] toArray(T[] a) {
		T[] arr = (T[]) java.lang.reflect.Array.newInstance(a.getClass().getComponentType(), size) ;
		int i = 0 ;
		for (Node<E> temp = header; temp != null; temp = temp.next) {
			arr[i++] = (T) temp.item ;
		}
		if(a.length>size)
			a[size] = null ;

		return arr;
	}

	public boolean add(E e) {
		Node<E> newNode = new Node<E>(tail	, e, null);
		if(header == null){
			header = tail = new Node<E>(null,e,null);
			size++ ;
			return true ;
		}
		tail = tail.next = newNode;
		size++;
		return true;
	}

	public boolean remove(Object o) {
		if(size == 0)
			return false ;
		if(o == null){
			for (Node<E> node = header ; node != null ; node = node.next) {
				if(node.item == null){
					removeNode(node);
					return true ;
				}
			}
		}else{
			for (Node<E> node = header ; node != null ; node = node.next) {
				if(o.equals(node.item)){
					removeNode(node);
					return true ;
				}
			}
		}
		return false;
	}
	
	/**
	 * 刪除鏈表中的節點
	 * @param node
	 */
	private void removeNode(Node<E> node) {
		if (node.pre == null) {
			header = node.next;
		}else{
			node.pre.next = node.next;
		}
		
		if(node.next == null){
			tail = node.pre ;
		}else{
			node.next.pre = node.pre ;
		}
		size-- ;
	}

	public boolean containsAll(Collection<?> c) {
		for (int i = 0; i < c.size(); i++) {
			Iterator<?> iter = c.iterator() ;
			while(iter.hasNext()){
				if(!contains(iter.next()))
					return false ;
			}
		}
		return true ;
	}

	public boolean addAll(Collection<? extends E> c) {
		if(c.size() == 0)
			return false ;
		for (int i = 0; i < c.size(); i++) {
			Iterator<? extends E> iter = c.iterator() ;
			while(iter.hasNext()){
				add(iter.next());
			}
		}
		return true;
	}

	public boolean addAll(int index, Collection<? extends E> c) {
		if(c.size() == 0)
			return false ;
		for (int i = 0; i < c.size(); i++) {
			Iterator<? extends E> iter = c.iterator() ;
			while(iter.hasNext()){
				add(index+i ,iter.next());
			}
		}
		return false;
	}
	
	public boolean removeAll(Collection<?> c) {
		if((c == null)||(c.size() == 0))
			return false ;
		for (int i = 0; i < c.size(); i++) {
			Iterator<?> iter = c.iterator() ;
			while(iter.hasNext()){
				remove(iter.next());
			}
		}
		return false;
	}
	/**
	 * 求兩個集合的交集，如果不存在返回 false
	 */
	public boolean retainAll(Collection<?> c) {
		if((c == null)||(c.size() == 0))
			return false ;
		boolean flag = false ;
		Iterator<?> iter = this.iterator() ;
		while(iter.hasNext()){
			if(!c.contains(iter.next())){
				iter.remove();
				flag = true ;
			}
		}
		return flag ;
	}

	public void clear() {
		header = tail = null ;
		size = 0 ;
	}

	public E get(int index) {
		checkBounds(index);
		Node<E> node = header ;
		for (int i = 0; i < index; i++) {
			node = node.next ;
		}
		return node.item;
	}

	/**
	 * 數據替換
	 */
	public E set(int index, E element) {
		checkBounds(index);
		Node<E> oldValue = header ;
		
		for (int i = 0; i < index; i++) {
			oldValue = oldValue.next ; 
		}
		E oldItem = oldValue.item ;
		oldValue.item = element ;
		return oldItem;
	}

	public void add(int index, E element) {
		checkAddBounds(index);
		Node<E> node = header ;
		for (int i = 0; i < index; i++) {
			node = node.next ;
		}
		if(size == 0){
			header = tail = new Node<E>(null, element, null);
		}else{
			if(node == null){
				tail = tail .next = new Node<E>(tail,element,node);
			}else{
				Node<E> newNode = new Node<E>(node.pre,element,node);
				if(node.pre == null){
					header = node.pre = newNode ;
				}else{
					node.pre = node.pre.next = newNode ;
				}
			}
		}
		size++ ;
	}

	private void checkAddBounds(int index) {
		if((index < 0)||(index > size))
			throw new IndexOutOfBoundsException();
	}

	private void checkBounds(int index) {
		if((index < 0)||(index >= size))
			throw new IndexOutOfBoundsException();
	}

	public E remove(int index) {
		checkBounds(index);
		Node<E> node = header ;
		for (int i = 0; i < index; i++) {
			node = node.next ;
		}
		removeNode(node);
		return  node.item;
	}

	public int indexOf(Object o) {
		int i = 0 ;
		for (Node<E> x = header; x != null ; x = x.next , i++) {
			if(o == null){
				if(x.item == null)
					return i ;
			}else{
				if(o.equals(x.item))
					return i ;
			}
		}
		return -1;
	}

	public int lastIndexOf(Object o) {
		int i = 0 ;
		for (Node<E> x = tail; x != null ; x = x.pre , i++) {
			if(o == null){
				if(x.item == null)
					return size - i ;
			}else{
				if(o.equals(x.item))
					return size - i ;
			}
		}
		return -1;
	}

	public ListIterator<E> listIterator() {
		// TODO 與迭代器相關的內容
		return null;
	}

	public ListIterator<E> listIterator(int index) {
		// TODO 與迭代器相關的內容
		return null;
	}

	public List<E> subList(int fromIndex, int toIndex) {
		if( (fromIndex < 0) || (toIndex > size) )
			throw new IndexOutOfBoundsException();
		if( fromIndex > toIndex)
			throw new IllegalArgumentException();
		MyLinkedList<E> sub = new MyLinkedList<E>() ;
		int i = 0 ;
		Node<E> node = header ;
		for (; i < fromIndex; i++) {
			node = node.next ;
		}
		for (;  i< toIndex; i++) {
			sub.add(node.item);
			node = node.next ;
		}
		return sub;
	}

	private static class Node<E>{
		Node<E> pre ;
		E item ;
		Node<E> next ;
		public Node(Node<E> pre , E e, Node<E> next) {
			this.pre = pre ;
			this.item = e ;
			this.next = next ;
		}
	}
	
}