JAVA单向链表的实现

package com.leo_faith.www;

public class Node {
    Object data;

    Node next;

    Node(Object d) {
        data = d;
        next = null;
    }
}

package com.leo_faith.www;

public class Node {
	Object data;

	Node next;

	Node(Object d) {
		data = d;
		next = null;
	}
}

 

package com.leo_faith.www;

public class LinkList {

    /* 用变量来实现表头 */
    private Node Head = null;

    private Node Tail = null;

    private Node Pointer = null; //point to previous

    private int Length = 0;

    public void deleteAll() {// 清空整个链表
        Head = null;
        Tail = null;
        Pointer = null;
        Length = 0;
    }

    // 链表复位，使第一个节点成为当前节点
    public void reset() {
        Pointer = null;
    }

    // 判断链表是否为空
    public boolean isEmpty() {
        return (Length == 0);
    }

    // 判断当前结点是否为最后一个结点
    public boolean isEnd() {
        if (Length == 0)
            throw new java.lang.NullPointerException();
        else if (Length == 1)
            return true;
        else
            return (cursor() == Tail);
    }

    // 返回当前结点的下一个结点的值，并使其成为当前结点
    public Object nextNode() {
        if (Length == 1)
            throw new java.util.NoSuchElementException();
        else if (Length == 0)
            throw new java.lang.NullPointerException();
        else {
            Node temp = cursor();
            Pointer = temp;
            if (temp != Tail)
                return (temp.next.data);
            else
                throw new java.util.NoSuchElementException();
        }
    }

    // 返回当前结点的值
    public Object currentNode() {
        Node temp = cursor();
        return temp.data;
    }

    // 在当前结点前插入一个结点，并使其成为当前结点
    public void insert(Object obj) {
        Node e = new Node(obj);
        if (Length == 0) {
            Tail = e;
            Head = e;
        } else {
            Node temp = cursor();
            e.next = temp;
            if (Pointer == null)
                Head = e;
            else
                Pointer.next = e;
        }
        Length++;
    }

    // 返回链表的大小
    public int size() {
        return Length;
    }

    // 将当前结点移出链表，下一个结点成为当前结点，
    // 如果移出的结点是最后一个结点，
    // 则第一个结点成为当前结点
    public Object remove() {
        Object temp;
        if (Length == 0)
            throw new java.util.NoSuchElementException();
        else if (Length == 1) {
            temp = Head.data;
            deleteAll();
        } else {
            Node cur = cursor();
            temp = cur.data;
            if (cur == Head)
                Head = cur.next;
            else if (cur == Tail) {
                Pointer.next = null;
                reset();
            } else
                Pointer.next = cur.next;
            Length--;
        }
        return temp;
    }

    // 返回当前结点的指针
    private Node cursor() {
        if (Head == null)
            throw new java.lang.NullPointerException();
        else if (Pointer == null)
            return Head;
        else
            return Pointer.next;
    }

    // 链表的简单应用举例
    public static void main(String[] args) {
        LinkList a = new LinkList();
        for (int i = 1; i <= 10; i++)
            a.insert(new Integer(i));
        System.out.println("The currentNode is:" + a.currentNode());
        while (!a.isEnd())
            System.out.println("The nextNode is:" + a.nextNode());
        a.reset();
        while (!a.isEnd()) {
            a.remove();
        }
        a.remove();
        a.reset();
        if (a.isEmpty()) {
            System.out.println("There is no Node in List");
        }
    }
}