package com.wyl.linklist;

/**
 * 雙向鏈表，實現26個字母的循環輸出
 * @author wyl
 *
 */
public class MyBinaryLink {

    private Node head; //定義雙線鏈表的頭結點
    /**
     * 定義雙向鏈表的節點類
     */
    class Node{
        private char data; //節點的值
        private Node prior; //前驅節點
        private Node next; //後繼節點
        public Node() {
        }
        
 
public Node(char data) {
            this(data, null, null);
        }
        public Node(char data, Node prior, Node next) {
            this.data = data;
            this.prior = prior;
            this.next = next;
        }
        public char getData() {
            return data;
        }
        
 
public void setData(char data) {
            this.data = data;
        }
        public Node getPrior() {
            return prior;
        }
        public void setPrior(Node prior) {
            this.prior = prior;
        }
        public Node getNext() {
            return next;
        }
        
 
public void setNext(Node next) {
            this.next = next;
        }
    }
    /**
     * 構造函數初始化雙向鏈表
     */
    public MyBinaryLink(){
        head = new Node(‘A‘, null, null);
        Node p = head;
        int i=1;
        for(;i<26;i++){
            if(p.next == null){
                char data = (char) (‘A‘ + i);
                Node newNode = new Node(data, p, null);
                p.next = newNode;
                p = p.next;
            }
        }
        p.next = head;
        head.prior = p;
    }
    /**
     * 打印雙向鏈表的值
     */
    public void print(){
        Node p = head;
        while(p.next != head){
            System.out.print(p.data + "、");
            p = p.next;
        }
        System.out.print(p.data);
    }
    
    /**
     * 從鏈表的某個位置開始打印
     * @param num 表示從鏈表的第幾個位置開始打印
     */
    public void printFrom(int num){
        int i = 1;
        Node p = head;
        Node rear = head.prior; //找到鏈表的尾節點
        Node start ;
        if(num > 0){
            for(;i<num;i++){
                p = p.next;
            }
            start = p;
            while(p.next != start){
                System.out.print(p.data);
                p = p.next;
            }
            System.out.print(p.data);
        }else{
            for(;i<-num;i++){
                rear = rear.prior;
            }
            start = rear;
            while(rear.next != start){
                System.out.print(rear.data);
                rear = rear.next;
            }
            System.out.print(rear.data);
        }
    }
    public static void main(String[] args) {
        MyBinaryLink myBinaryLink = new MyBinaryLink();
        myBinaryLink.print();
        System.out.println();
        myBinaryLink.printFrom(4);
        System.out.println();
        myBinaryLink.printFrom(-2);
    }
}

雙向鏈表實例