[Java]单项链表与双端链表[原]

package com.black.datastructures.link; /**  * 链接点  *  * @author BlackWinter  *  * @date 2010-7-7 下午10:45:24  *  * @file com.black.datastructures.link.Link.java  *  * @version 1.0  */ public class Link {     public int key;     public double value;     public Link next;     public Link(int id, double date) {         this.key = id;         value = date;     }     public void displayLink() {         System.out.printf("{%s,%s}\n", key, value);     } }

package com.black.datastructures.link; /**  * 单向链表  *  * @author BlackWinter  *  * @date 2010-7-7 下午10:35:10  *  * @file com.black.datastructures.link.LinkList.java  *  * @version 1.0  */ public class LinkList {     private Link first;     public LinkList() {         first = null;     }     public boolean isEmpty() {         return first == null;     }     /* 在链表头部插入新节点 */     public void insertFirst(int id, double date) {         Link link = new Link(id, date);         link.next = first;         first = link;     }     /* 删除链表的头部节点 */     public Link deleteFirst() {         Link temp = first;         first = first.next;         return temp;     }     /* 根据key查询指定的链接点 */     public Link find(int key) {         Link current = first;         while (current.key != key) {             if (current.next == null)                 return null;             else                 current = current.next;         }         return current;     }          /* 根据key删除指定节点 */     public Link delete(int key) {         Link current = first;         Link previous = first;         while (current.key != key) {             if (current.next == null)                 return null;             else {                 current = current.next;                 previous = current;             }         }         if (current == first)             first = first.next;         else             previous.next = current.next;         return current;     }     /* 显示链表的所有节点 */     public void displayList() {         System.out.println("First --> Last:");         Link current = first;         while (null != current) {             current.displayLink();             current = current.next;         }     } }

package com.black.datastructures.link; /**  * 双端链表  *  * @author BlackWinter  *  * @date 2010-7-11 下午09:09:12  *  * @file com.black.datastructures.link.DouEndLinkList.java  *  * @version 1.0  */ public class DouEndLinkList {     private Link first;     private Link last;     public DouEndLinkList() {         first = null;         last = null;     }     public boolean isEmpty() {         return first == null;     }     public void insertFirst(int id, double date) {         Link newLink = new Link(id, date);         if (isEmpty())             last = newLink;         newLink.next = first;         first = newLink;     }     public void insertLast(int id, double date) {         Link newLink = new Link(id, date);         if (isEmpty())             first = newLink;         else             last.next = newLink;         last = newLink;     }     public void display() {         System.out.println("List (first --> last):");         Link current = first;         while (null != current) {             current.displayLink();             current = current.next;         }     } }