现在对Java原生数据结构特感兴趣，于是决定自己动手实现一些类，比如这个List类，在熟习了单链表和双链表的数据结构之后，终于实现了，代码如下：
源码SingleLinkedList.java
package hk.inso.service;
/**
* Created by IntelliJ IDEA.
* Date: 8/10/15 6:09 PM
* Author: Richard
*/
public class SingleLinkedList<E> {
private static class Node<E> {
private E element;
private Node next;
public Node(E element) {
//constructor with args
this.element = element;
}
public Node() {
//constructor without args
}
@Override
public String toString() {
return element.toString();
}
}
private Node first;
private Node last;
/**
* 添加元素到链表头部
* @param element
*/
public void add(E element) {
Node<E> node = new Node<E>(element);
linkFirst(node);
}
/**
* 添加元素到链表尾部
* @param element
*/
public void addLast(E element) {
Node<E> node = new Node<E>(element);
linkLast(node);
}
/**
* 根据索引移除元素
* @param index
*/
public void remove(int index) {
if (index == 0) {
unlinkFirst();
}
else{
Node node = getNode(index);
unlink(node);
}
}
/**
* 移除链表中最后一个元素
*/
public void removeLast() {
unlinkLast();
}
/**
* 将元素插入指定链表索引为止
* @param index
* @param element
*/
public void insert(int index, E element) {
Node<E> node1 = new Node<E>(element);
if(index == 0) {
linkFirst(node1);
} else {
Node node2 = getNode(index);
link(node1, node2);
}
}
/**
* 获取某个元素
* @param index
* @return
*/
public E get(int index) {
Node<E> node = getNode(index);
E element = node.element;
return element;
}
/**
* 统计链表里面所有元素的个数
* @return 总的元素的个数
*/
public int size() {
int count = 0;
Node node = first;
while (node != null) {
count++;
node = node.next;
}
return count;
}
/**
* toString方法实现
* @return
*/
@Override
public String toString() {
Node node = first;
StringBuilder stringBuilder = new StringBuilder();
if(node == null) {
return "{}";
}
while (node != null) {
stringBuilder.append("[" + node.element.toString() +"],");
node = node.next;
}
String result = stringBuilder.toString();
int index = result.lastIndexOf(",");
return result.substring(0, index);
}
/**
* 插入结点到链表中间
* 插入前
* node2->node3->node4
* 插入后
* node2->node1->node3->node4
* @param node1 要插入的结点
* @param node2 插入结点位置结点
*/
private void link(Node node1, Node node2) {
node1.next = node2;
Node prevNode = getPrevNode(node2);
prevNode.next = node1;
}
/**
* 插入结点到链表首部
* @param node
*/
private void linkFirst(Node node) {
if(first == null || last == null) {
first = last = node;
} else {
node.next = first;
first = node;
}
}
/**
* 插入结点到链表尾部
* @param node
*/
private void linkLast(Node node) {
last.next = node;
last = node;
}
/**
* 从链表中间移除当前结点
* @param node
*/
private void unlink(Node node) {
Node prevNode = getPrevNode(node);
prevNode.next = node.next;
}
/**
* 移除头部的结点
*/
private void unlinkFirst() {
first = first.next;
}
/**
* 移除尾部的结点
*/
private void unlinkLast() {
Node prevNode = getPrevNode(last);
prevNode.next = null;
last = prevNode;
}
/**
* 寻找当前结点的前一个结点
* @param node 当前结点
* @return
*/
private Node getPrevNode(Node node) {
//这里多走了一步
// Node nodeItr = first.next;
Node nodeItr = first;
Node prevNode = new Node();
while (!nodeItr.equals(node)) {
prevNode = nodeItr;
nodeItr = nodeItr.next;
}
return prevNode;
}
/**
* 根据索引查找链表中得数据
* @param index
* @return 链表结点
*/
private Node getNode(int index) {
Node node = first;
Node currentNode = new Node();
if (index == 0) {
//continue
}
if (index >= size()) {
throw new IndexOutOfBoundsException(errMessage(index));
}
else {
int i = 0;
while (i <= index) {
if(node != null) {
currentNode = node;
//注意这里有递增
node = node.next;
}
i++;
}
}
return currentNode;
}
/**
* 错误消息显示
* @param index
* @return
*/
private String errMessage(int index) {
return "Size: "+ size() + ", index: "+ index;
}
}
测试方法TestSingleLinkedList.java
package hk.inso.test;
import hk.inso.service.SingleLinkedList;
/**
* Created by IntelliJ IDEA.
* Date: 8/11/15 4:58 PM
* Author: Richard
*/
public class TestSingleLinkedList {
public static void main(String[] args) {
SingleLinkedList<User> list = new SingleLinkedList<User>();
list.add(new User(5, "Jimmy", "Girl"));
list.add(new User(7, "Tom", "Boy"));
list.addLast(new User(6, "Amy", "Girl"));
System.out.println(list.toString());
}
}
class User {
private int age;
private String name;
private String gender;
public User(int age, String name, String gender) {
this.age = age;
this.name = name;
this.gender = gender;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
@Override
public String toString() {
return "User{" +
"age=" + age +
", name=‘" + name + ‘\‘‘ +
", gender=‘" + gender + ‘\‘‘ +
‘}‘;
}
}
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