Why is it important to override the hashCode method in your classes?

Overriding the hashCode method is important for objects to work correctly in hash-based collections (e.g., HashMap, HashSet).

Rules:

• If two objects are equal according to the equals() method, then their hashCode() must return the same value.
• If hashCode is not overridden, objects with the same data may have different hashes, leading to incorrect collection behavior.

Example:

@Override
public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;
    Person person = (Person) o;
    return Objects.equals(id, person.id);
}

@Override
public int hashCode() {
    return Objects.hash(id);
}

Here, id is a unique identifier of the object.