java linkedhashmap 使用实例

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;
	}
	
	@Override
	public 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;
	}
	
	@Override
	public 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;
	}
	
	@Override
	public String toString() {
		String ret = name + " " + this.age + " " + this.money;
		return ret;
	}
}

accessOrder为false
liping 1 1.01 1
liping 2 1.02 2
liping 3 1.03 3
accessOrder为true
liping 2 1.02 2
liping 1 1.01 1
liping 3 1.03 3