Why is Lombok @Builder not compatible with this constructor?

Question

I have this simple code:

@Data
@Builder
public class RegistrationInfo {

    private String mail;
    private String password;

    public RegistrationInfo(RegistrationInfo registrationInfo) {
        this.mail = registrationInfo.mail;
        this.password = registrationInfo.password;
    }
}

First I was using only the @Builder Lombok annotation and everything was fine. But I added the constructor and the code does not compile any more. The error is:

Error:(2, 1) java: constructor RegistrationInfo in class com.user.RegistrationInfo cannot be applied to given types;
  required: com.user.RegistrationInfo
  found: java.lang.String,java.lang.String
  reason: actual and formal argument lists differ in length

So I have two questions:

Why is Lombok @Builder not compatible with this constructor?
How do I make the code compile taking into account that I need both the builder and the constructor?

From the error, i assume that 1) incorrect number of parameters in the constructor 2) incorrect parameters type is passed to the constructor — Marios Nikolaou, Jul 01 '18 at 10:25
Does that happen for all constructors or for that particular one? Do you get an error even if you change parameters of constructor? — wdc, Jul 01 '18 at 10:25
@wdc I have only one constructors (which is mentioned in the code). I need constructor with this parameter to be able to copy the object. — IKo, Jul 01 '18 at 10:30
Did you check `@Builder(toBuilder = true)` ? This suppose to give you functionality of copy constructor. `Foo copy = original.toBuilder().build()` — wdc, Jul 01 '18 at 10:37
@wdc just tried your solution. It's even better then with the constructor. Thanks! — IKo, Jul 01 '18 at 10:55

score 62 · Accepted Answer · edited Aug 28 '23 at 09:19

62

You can either add an @AllArgsConstructor annotation, because

@Builder generates an all-args constructor if there are no other constructors defined.

(Quoting @Andrew Tobilko)

Or set an attribute to @Builder : @Builder(toBuilder = true) This give you the functionality of a copy constructor.

@Builder(toBuilder = true)
class Foo {
    // fields, etc
}

Foo foo = getReferenceToFooInstance();
Foo copy = foo.toBuilder().build();

edited Aug 28 '23 at 09:19

RubioRic

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answered Jul 01 '18 at 10:59

wdc

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though it is a more concise way and [is backed up by the author](https://stackoverflow.com/a/47093799/4922375), it is also counter-intuitive and involves the creation of an unnecessary instance (`foo.toBuilder()` here) – Andrew Tobilko Jul 01 '18 at 11:36

score 33 · Answer 2 · edited Sep 11 '22 at 08:47

33

When you provide your own constructor then Lombok doesn't create a constructor with all args that @Builder is using. So you should just add annotation @AllArgsConstructor to your class:

@Data //try to avoid as it's an anti-pattern
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class RegistrationInfo {
    //...
}

edited Sep 11 '22 at 08:47

jumping_monkey

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answered Jul 01 '18 at 10:49

Cepr0

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score 13 · Answer 3 · edited May 06 '22 at 08:19

13

Presumably, @Builder generates an all-args constructor if there are no other constructors defined.

@Data
@Builder
@AllArgsConstructor(access = AccessLevel.PRIVATE)
class RegistrationInfo {

    private String mail;
    private String password;

    private RegistrationInfo(RegistrationInfo registrationInfo) {
        this(registrationInfo.mail, registrationInfo.password);
    }
}

edited May 06 '22 at 08:19

rjdkolb

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answered Jul 01 '18 at 10:49

Andrew Tobilko

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2

In my case, I use the default constructor so I was forced to also add this annotation `@NoArgsConstructor` – Bludwarf Apr 10 '19 at 10:20

Why is Lombok @Builder not compatible with this constructor?

3 Answers3

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