Why is Lombok @Builder not compatible with this constructor?

问题

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?

回答1:

You can either add an @AllArgsConstructor annotation, because

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

(Quotting @Andrew Tobilko)

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

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

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

回答2:

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

@Data
@Builder
@AllArgsConstructor
public class RegistrationInfo {
    //...
}

回答3:

Presumably, @Builder generates an all-args constructor iff 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);
    }
}

来源：https://stackoverflow.com/questions/51122400/why-is-lombok-builder-not-compatible-with-this-constructor

标签

java

Lombok