Implement hashCode and equals

Problem For a custom class (e.g. Person{name, age, email}), implement equals() and hashCode() honoring their contract.

Input / Output

• equals(Object o): logical equality over significant fields; hashCode(): int consistent with equals.

Constraints

• Contract: equal objects MUST have equal hash codes; hashCode must be consistent across calls; equals must be reflexive, symmetric, transitive, null-safe (equals(null) → false).

Example

• new Person("A", 30) and new Person("A", 30) → equals true, same hashCode → usable as HashMap keys; violating this makes map.get() miss entries.