Is there a map or list in java that allows associating two objects with eachother? [duplicate]

Question

I would need a list/map like a HashMap where i can easily access either 'side' by simple passing the object and retrieving the other thing.

I need to be able to use get(key) and retrieve the value as well as get(value) and retrieve the key AND i want to be able to set a new key or value.

Is there already something like that ?

Answer 1

Two popular choices are

• Guava's BiMap
• Apache Commons BidiMap