Java HashMap是按键排序的

import java.util.HashMap;public class testMain {/** * @param args */public static void main(String[] args) {new testMain();}public testMain(){HashMap<Integer, String> arr = new HashMap<Integer, String>();arr.put(3,"c");arr.put(2,"b");arr.put(4,"d");arr.put(1,"a");for(int key: arr.keySet())System.out.println(key+"=>"+arr.get(key));}}

 

1=>a2=>b3=>c4=>d