[Guava]——BiMap

public class demo7 {//hashmap，键唯一，值可以重复,BiMap:双向Map(Bidrectional Map)键与值都不能重
public static void main(String[] args) {
BiMap<String, String> biMap=HashBiMap.create();
biMap.put("abcd", "abcdm@qq.com");
biMap.put("chance", "chance@qq.com");
//通过邮箱找用户,通过值找Key
String user=biMap.inverse().get("chance@qq.com");
System.out.println(user);
}
}