In a Map we can lookup for a value by using a distinct key. In a Map

with reverse view and lookup, even the values are distinct. So there

is one to one mapping between keys and values and vice version.

If we enable this constraint on a Map then we can look up a key by

its value. Such data structure is called bi-directional map.

There is no built data structure similar to reverse lookup Map in

JDK.

But Apache Common Collections and Guava libraries provide

implementation of bidirectional map. It is called BidiMap and

BiMap. Both of these data structure enforce the constraint of one to

one mapping between keys and values.

https://www.techiedelight.com/invert-mapping-map-java/