calling containsKey on a hashmap with custom class

Question

I have a Color class that I\'m putting in the hashmap. I\'d like to call containsKey on the hashmap to ensure whether the object is already present in the hashm

Answer 1

Your custom class Color should override equals() and hashcode() methods to achieve what you want.

When you are using custom objects as keys for collections and would like to do lookup using object, then you should properly override equals() and hashcode() methods.

Also read:

Overriding equals and hashCode in Java