java linkedhashmap 使用实例

来源：互联网发布：台湾天心软件编辑：程序博客网时间：2024/05/18 02:09

下面的代码记录了linkedhashmap的使用，重点是对accessOrder的使用说明，起增删改查的使用和hashmap是一样的，没有什么不同，具体可以参考hashmap的使用

accessOrder为false的时候，linkedhashmap在遍历的时候可以保证插入顺序，即先插入的元素在迭代的时候先输出；

accessOrder为true的时候，linkedhashmap在遍历的时候不保证插入顺序，会将最后访问的元素，放在链表的最后，迭代的时候最后输出，下面是实例代码和输出

package com.basic.util;import java.util.Iterator;import java.util.LinkedHashMap;import java.util.Map.Entry;public class BasicLinkedHashMap {public static void main(String[] args) {NewPerson p1 = new NewPerson("liping", 1, 1.01);NewPerson p2 = new NewPerson("liping", 2, 1.02);NewPerson p3 = new NewPerson("liping", 3, 1.03);LinkedHashMap<NewPerson, Integer> mapPerson = new LinkedHashMap<NewPerson, Integer>(16, 0.75f, false);mapPerson.put(p1, 1);mapPerson.put(p2, 2);mapPerson.put(p3, 3);mapPerson.get(p1);mapPerson.get(p3);Iterator<Entry<NewPerson, Integer>> iter = mapPerson.entrySet().iterator();while (iter.hasNext()) {Entry<NewPerson, Integer> e = iter.next();System.out.println(e.getKey() + " " + e.getValue());}}}class NewPerson {private String name;private int age;private double money;public NewPerson(String name, int age, double money) {this.name = name;this.age = age;this.money = money;}@Overridepublic boolean equals(Object obj) {if (!(obj instanceof NewPerson)) {return false;}NewPerson p = (NewPerson) obj;if (!p.name.equals(this.name)) {return false;}if (p.age != this.age) {return false;}if (p.money != this.money) {return false;}return true;}@Overridepublic int hashCode() {final int prime = 31;int result = 1;result = result*prime + this.name.hashCode();result = result*prime + this.age;result = result*prime + (int) Double.doubleToLongBits(this.money);return result;}@Overridepublic String toString() {String ret = name + " " + this.age + " " + this.money;return ret;}}

输出结果如下：

accessOrder为falseliping 1 1.01 1liping 2 1.02 2liping 3 1.03 3accessOrder为trueliping 2 1.02 2liping 1 1.01 1liping 3 1.03 3

0 0