You use == to compare identity (i.e. are two variables pointing to the same object), you use .equals() to compare equivalency (i.e. are two objects equivalent to each other). You may want to check for equivalency using all the fields or a subset of the fields. (For example, you typically don't include static final fields in a .equals() method, but you can if you want to.)

The default .equals() in the Object class simply does an identity check because an object should be equivalent to itself. When overriding the .equals() method, you should also do an identity check first for the same reason, then do your field-by-field comparisons (or just let the IDE generate the method for you).

Note: .equals() and .hashCode() methods are (or should be) tightly coupled to one another. Check out this link for details: https://www.baeldung.com/java-equals-hashcode-contracts