javalombok

Required arguments with a Lombok @Builder


If I add @Builder to a class. The builder method is created.

Person.builder().name("john").surname("Smith").build();

I have a requirement where a particular field is required. In this case, the name field is required but the surname is not. Ideally, I would like to declare it like so.

Person.builder("john").surname("Smith").build()

I can't work out how to do this. I have tried adding the @Builder to a constructor but it didn't work.

@Builder
public Person(String name) {
    this.name = name;
}

Solution

  • You can do it easily with Lombok annotation configuration

    import lombok.Builder;
    import lombok.ToString;
    
    @Builder(builderMethodName = "hiddenBuilder")
    @ToString
    public class Person {
    
        private String name;
        private String surname;
    
        public static PersonBuilder builder(String name) {
            return hiddenBuilder().name(name);
        }
    }
    

    And then use it like that

    Person p = Person.builder("Name").surname("Surname").build();
    System.out.println(p);
    

    Of course @ToString is optional here.