Key by value, value by key classes in Java standrad libraries

Question

Tell me please, there any methods in standard library for implementation some simple dictionary look like: "a=10,b=11,c=12...". I know about HashMap, but as I know we can`t get key by value, just value by key.

There is no meaning of look up by value because it can be duplicated and can result in multiple keys. — Braj, Apr 16 '14 at 18:30
i have alphabet. do you see some alphabet with two equals letters? i hope that java have more ways for this problem without entryset — mechanikos, Apr 16 '14 at 18:37
How many values do you have in your map? Are key and value both unique? — Braj, Apr 16 '14 at 18:50

score 2 · Accepted Answer · answered Apr 16 '14 at 19:01

if key & value are all identify, and 1 to 1, then you can write a class which have 2 Map,
1 Map store key:value, another store value:key, so that you can do search in both way.

Also, if key & value have fixed relationship which could be convert by a function, then you can use that function to convert key & value to each other.

score 1 · Answer 2 · answered Apr 16 '14 at 18:19

1

Take a look at Guava BiMap. Seems what you're looking for.

http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/collect/BiMap.html

answered Apr 16 '14 at 18:19

Andres

10,181
4
40
61

They did say the standard library. – Thom Apr 16 '14 at 18:21

Key by value, value by key classes in Java standrad libraries

2 Answers2