HashMap 根据Value获取Key

package com.other; import java.util.ArrayList; import java.util.HashMap; import java.util.Map; public class HashMapDemo { //获取一个Key public static Object getKey(HashMap hm,String value){ Object key=null; for(Object getKey:hm.keySet()){ if (hm.get(getKey).equals(value)) { key=getKey; } } return key; } //获取所有Key public static ArrayList getAllKey(HashMap hm,String value){ ArrayList list=new ArrayList(); for(Object getKey:hm.keySet()){ if (hm.get(getKey).equals(value)) { list.add(getKey); } } return list; } //测试类 public static void main(String[] args) { HashMap hm=new HashMap(); hm.put("CHINA", "中国"); hm.put("CN", "中国"); //获取一个Key System.out.println("通过Value获取Key:"+getKey(hm,"中国")); //获取所有Keys ArrayList list=getAllKey(hm,"中国"); for(int i=0;i<list.size();i++){ System.out.println(list.get(i)); } } }