How can I have a HashMap with unique keys in java?

Question

How can I have a HashMap with unique keys in Java? Or even does this make any sense to have unique keys in HashMap or the keys are unique by default? I am a newbie. thx

Answer 1

Try to look at the Java API for Map which is interface that HashMap implements. The first sentence is:

An object that maps keys to values. A map cannot contain duplicate keys; each key can map to at most one value.