What functions need to be rewritten to ensure the correct operation of the HashSet collection?

To ensure the correct functioning of the HashSet collection in Java, you need to override the hashCode() and equals() methods in your class.

• hashCode() should return the hash code of the object, which is used for quick lookup in the hash table.
• equals() determines when two objects are considered equal.

If these methods are not correctly overridden, HashSet may incorrectly determine the uniqueness of objects, leading to duplicates or the inability to find an object.

Example:

@Override
public boolean equals(Object obj) {
    if (this == obj) return true;
    if (obj == null || getClass() != obj.getClass()) return false;
    MyClass other = (MyClass) obj;
    return Objects.equals(field1, other.field1) && field2 == other.field2;
}

@Override
public int hashCode() {
    return Objects.hash(field1, field2);
}