Java: When should I override equals?
hashCode) if and only if your class represents some form of value or entity.
Should override equals:
CommandShould not override equals:
Regarding Mutable classes
It is often good practice to make classes representing values and entities immutable. (What exactly is immutable?) If this is not an option in your situation, think twice before overriding
equals. Imagine what could happen if the equality of two objects changes between the point where
equals is called, and the point where the code actually relies value returned by the
equals call. As a concrete example, using mutable objects (with custom
hashCode implementations) as keys in hash maps is a big no no!