HashMap根据value获取key值

Posted 2020-10-06 kim_liu

public static String getCityId(HashMap<String,String> citys, String city){
    Set set = citys.entrySet();//新建一个不可重复的集合
    ArrayList<String> arr = new ArrayList<String>();//新建一个集合
    Iterator it = set.iterator();//遍历的类
    while(it.hasNext()) {
        Map.Entry entry = (Map.Entry)it.next();//找到所有key-value对集合
        if(entry.getValue().equals(city)) {//通过判断是否有该value值
            String s = (String) entry.getKey();//取得key值
            arr.add(s);
        }
    }
   return arr.get(0);
}