java实现双向链表

自定异常类：

public class MyException extends Exception {
	
	public MyException(){};
	
	public MyException(String msg){
		super(msg);
	}

}

链表结点对像：

public class Node {
	
	public Node previou=null;//前结点指针
	public Node next=null;   //后结点指针
	public Object value;//结点值
	
	Node(Object value){
		this.value=value;
	}

}

链表对像：

public class DoubleLinked {

	private Node head;//链表头
	
	DoubleLinked(){
		
	}
	/**
	 * 判断是否还有下一个结点，没有则为链表的尾结点
	 * @param node
	 * @return
	 */
	public boolean hasNext(Node node){
		
		if(node.next==null)
			return false;
		return true;
	}
	/**
	 * 判断是否有上一个结点，没有则为链表的头结点
	 * @param node
	 * @return
	 */
	public boolean hasPrev(Node node){
		
		if(node.previou==null)
			return false;
		return true;
	}
	/**
	 * 获取链表头元素
	 * @return
	 * @throws MyException 
	 */
	public Node getHead() throws MyException{
		if(head==null){
			throw new MyException("链表为空");
		}
		return head;
	}
	/**
	 * 获取上一个接点
	 * @param node
	 * @return
	 */
	public Node getPrev(Node node){
	
		return node.previou;
	}
	/**
	 * 获取下一个结点
	 * @param node
	 * @return
	 */
	public Node getNext(Node node){
		return node.next;
	}
	/**
	 * 根据索引获取结点
	 * @param index：结点索引
	 * @return
	 * @throws MyException 
	 */
	public Node getNode(int index) throws MyException{
		
		Node curNode=null;
		Node next=null;
		Node node=null;
		
		if(head==null){
			throw new MyException("链表为空");
		}else{
			curNode=head;
			for(int i=0;i<index;i++){
				if(curNode==null){
					throw new MyException("你要获取的元素索引大于链表长度");
				}else{
					node=curNode;
					if(hasNext(curNode)){
						next=curNode.next;
						curNode=next;
					}else{
						curNode=null;
					}
				}
			}
		}
		return node;
	}
	/**
	 * 获取最后一个结点
	 * @return
	 * @throws MyException 
	 */
	public Node getLast() throws MyException{
		
		Node curNode=null;
		Node next=null;
		Node last=null;
		boolean flag=true;
		
		if(head==null){
			throw new MyException("链表为空");
		}else{
			curNode=head;			
			while(flag){
				if(hasNext(curNode)){
					next=curNode.next;
					curNode=next;
				}else{
					last=curNode;
					flag=false;
				}
				
			}
		}
		return last;
	}
	/**
	 * 在链表头添加新结点
	 * @param node
	 */
	public void addHead(Node node){
		
		if(head==null){
			head=node;
		}else{
			node.next=head;
			head.previou=node;
			head=node;
		}
	}
	/**
	 * 在链表末尾处添加新结点
	 * @param node
	 * @throws MyException 
	 */
	public void addLast(Node node) throws MyException{
		
		if(head==null){
			head=node;
		}else{
			Node last=this.getLast();
			last.next=node;
			node.previou=last;
		}
	}
	/**
	 * 在链表中间插入新结点
	 * @param node
	 * @throws MyException 
	 */
	public void insertNode(int index,Node node) throws MyException{
		
		Node indexNode=this.getNode(index);
		Node prev=indexNode.previou;
		
		prev.next=node;
		node.previou=prev;
		node.next=indexNode;
		indexNode.previou=node;
	}
	/**
	 * 删除链表头结点
	 * @return
	 * @throws MyException 
	 */
	public Node deleteHead() throws MyException{
		
		Node head=this.getHead();
		
		if(hasNext(head)){
			Node next=head.next;
			this.head=next;
			next.previou=null;
		}
		return head;
	}
	/**
	 * 删除链表的最后一个结点
	 * @return
	 * @throws MyException 
	 */
	public Node deleteLast() throws MyException{
		
		Node last=this.getLast();
		Node prev=last.previou;
		
		if(prev==null){
			this.head=null;
		}else{
			prev.next=null;
		}
		return last;
	}
	/**
	 * 根据索引删除链表结点
	 * @param index
	 * @return
	 * @throws MyException 
	 */
	public Node deleteNode(int index) throws MyException{
		
		Node node=this.getNode(index);
		Node prev=node.previou;
		Node next=node.next;
	
		if(prev==null && next!=null){
			this.head=next;
			next.previou=null;
		}
		if(prev!=null && next==null){
			prev.next=null;
		}
		if(prev==null && next==null){
			this.head=null;
		}
		if(prev!=null && next!=null){
			prev.next=next;
			next.previou=prev;
		}
		
		return node;
	}
	
	
} :!: