Inheritance for builders in lombok

Question

I was trying to use lombok for my project.

I have a class A:

@Data
@Builder
public class A {
    Integer a1;
}

and a class B:

@Data
public class B extends A {
    Integer b1;

    @Builder
    public B(Integer b1, Integer a1) {
        super(a1);
        this.b1 = b1;
    }
}

I am getting an error saying builder() in B cannot override builder() in A, as return type in BBuilder is not compatible with return type in ABuilder.

Is there some way to do this using lombok? I do not want to write the complete builder for for B, unless I don't have any other option.

PS: I have given explicit constructor for class B due to Issue. I tried searching, but I could not find a good solution for the same.

score 26 · Accepted Answer · answered Jun 10 '16 at 16:07

26

Here we just need to call super of the builder.

@Data
public class B extends A {
    Integer b1;

    @Builder
    public B(Integer b1, Integer a1) {
        super(a1);
        this.b1 = b1;
    }

    public static class BBuilder extends ABuilder{
            BBuilder() {
                super();
            }
    }
}

answered Jun 10 '16 at 16:07

Abhinav Aggarwal

1,205
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24

10

This solution won't work if parent class has a @Builder annotation as well. – realPK Jul 12 '19 at 20:51

walv · Answer 2 · 2021-10-20T23:32:08.877

13

Both child and parent should be marked with @SuperBuilder.

Having both parent and child as @Builder won't work.

Parent class A:

@Data
@SuperBuilder
public class A {
    Integer a1;
}

Child class B:

@Data
@SuperBuilder
public class B extends A {
    Integer b1;
}

edited Oct 20 '21 at 23:32

answered Apr 30 '21 at 18:21

walv

2,680
3
31
36

score 11 · Answer 3 · answered Aug 07 '18 at 14:22

11

Lombok has introduced experimental features with version: 1.18.2 for inheritance issues faced with Builder annotation, and can be resolved with @SuperBuilder annotation

Please use lombok version: 1.18.2, @SuperBuilder annotations in child/parent class

answered Aug 07 '18 at 14:22

Amit Kaneria

5,466
2
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score 11 · Answer 4 · answered Jul 12 '19 at 20:57

If you are using Lombok 1.18.4 along with IntelliJ, following code shall work for you:

@Data
@Builder
class A {
    Integer a1;
}

@Data
class B extends A {
    Integer b1;

    @Builder (builderMethodName = "BBuilder")
    public B(Integer b1, Integer a1) {
        super(a1);
        this.b1 = b1;
    }
}

public class Main {

    public static void main(String[] args){
    System.out.println(B.BBuilder().a1(1).b1(1).build());

    }
}

One a side note, @SuperBuilder annotation didn't work in IntelliJ at time of writing this answer. If you have multiple level of inheritance, please avoid Lombok or it will make your Java models messy.

To clarify, this does not enable doing `A.builder()`, and `B.builder()`. — zr0gravity7, Dec 22 '22 at 18:49

Sanskar Agarwal · Answer 5 · 2022-11-29T21:05:59.110

After hours of hacking at this, I found a viable solution without using the @SuperBuilder. Consider an example -

public class A{
    int x;
    
    @Builder(toBuilder = true)
    public A(int x){
        this.x = x;
    }
    
    public static class ABuilder{
        protected ABuilder(){} //Note this is important, otherwise BBuilder won't be able to access private no-args constructor of ABuilder
    }
}

public class B extends A{
    
    @Builder(builderMethodName="BBuilder", toBuilder=true)
    public B(int x){
        super(x);
    }
    
    public static class BBuilder extends ABuilder{
        BBuilder(){
            super();
        }
    }
}

public static void main(){
    B obj = new B();
    //we can use the existing obj as  obj.toBuilder().x(5).build();
    //this will return an object of B and not A

}

P.S : I am not sure if @SuperBuilder is an experimental feature still ; so didn't want to take chances

Inheritance for builders in lombok

5 Answers5