How to correctly generate keys for HashMap and what type?

Question

Java

Is there any generally accepted way to generate keys and what should they be? While generating integer keys, the next key is an increment of the previous one. I look forward to links to resources, reasonable answers.

Answer 1

The key in a HashMap can be anything (even NULL ) The HashMap uses the result of the Object.hashCode() method as a key . On this occasion, Bloch is very well written, read

Answer 2

There is no generally accepted. Describe the task.