Warning equals/hashCode on @Data annotation lombok with inheritance

I have a entity which inherits from other. On other hand, I'm using lombok project to reduce boilerplate code, so I put @Data annotation. The annotation @Data with inheritance produces the next warning:

>Generating equals/hashCode implementation but without a call to superclass, even though this class does not extend java.lang.Object. If this is intentional, add @EqualsAndHashCode(callSuper=false) to your type.

Is it advisable to add annotation @EqualsAndHashCode (callSuper = true) or @EqualsAndHashCode (callSuper = false)? If it is not added, Which one is it callSuper=false or callSuper=true?

The default value is false. That is the one you get if you don't specify it and ignore the warning.

Yes, it is recommended to add an @EqualsAndHashCode annotation on the @Data annotated classes that extend something else than Object. I cannot tell you if you need true or false, that depends on your class hierarchy, and will need to be examined on a case-by-case basis.

However, for a project or package, you can configure in lombok.config to call the super methods if it is not a direct subclass of Object.

lombok.equalsAndHashCode.callSuper = call

See the configuration system documentation on how this works, and the @EqualsEndHashCode documentation for the supported configuration keys.

Disclosure: I am a lombok developer.

@EqualsAndHashCode(callSuper=true) should resolve the warning.

The main original question is:

> Is it advisable to add annotation @EqualsAndHashCode (callSuper = > true) or @EqualsAndHashCode (callSuper = false)?

The accepted answer is basically just:

> ...that depends...

To expand on that, the documentation on @EqualsAndHashCode has some solid guidance on which to choose. Especially this, IMHO:

> By setting callSuper to true, you can include the equals and hashCode > methods of your superclass in the generated methods. For hashCode, the > result of super.hashCode() is included in the hash algorithm, and > forequals, the generated method will return false if the super > implementation thinks it is not equal to the passed in object. Be > aware that not all equals implementations handle this situation > properly. However, lombok-generated equals implementations do handle > this situation properly, so you can safely call your superclass equals > if it, too, has a lombok-generated equals method.

To distill this down a bit: Chose 'callSuper=true' if you are inheriting from a superclass that either has no state information, or itself is using the @Data annotation, or has implementations of equals/hash that "handle the situation properly" - which I interpret to mean returning a proper hash of the state values.

If you want to compare the members of the superclass as well, then use @EqualsAndHashCode(callSuper=true). If, however, you only want to compare fields in the current class you can use @EqualsAndHashCode(callSuper=false) which is the default option.

If you use the Delombok-feature you can see that the difference is that when set to true this line is added to the generated equals method if (!super.equals(o)) return false;. If you have members in the superclass that should be taken into account when comparing two objects, then it has to be set to true to compare correctly.