Customizing Builder generated by Lombok

Question

I have defined a class with a builder and now I would like to limit boilerplate code using Lombok's @Builder annotation.

public class ClientApp {

    private UUID clientId;

    ClientApp(UUID clientId) {
      this.clientId = clientId;
    }

    public static Builder builder() {
      return new Builder();
    }

    public static class Builder {

      private UUID clientId;

      public Builder clientId(String clientId) {
        return clientId(UUID.fromString(clientId));
      }

      public Builder clientId(UUID clientId) {
        this.clientId = clientId;
        return this;
      }

      public ClientApp build() {
        return new ClientApp(this.clientId);
      }
    }

    public Builder clientId(String clientId) {
        return clientId(UUID.fromString(clientId));
    }
}

However, the annotation will not generate clientId(String) method, only clientId(UUID). How can I generate it with Lombok?

Answer 1

I could not get the @Tolerate method to work (I may be doing it wrong).

     /**
     * Fails with The method clientId(String) in the type So33943193.ClientApp.ClientAppBuilder is not applicable
     * for the arguments (UUID)
     */
    public static class ClientAppBuilder {

        @Tolerate
        public ClientAppBuilder clientId(String clientId) {
            return this.clientId(UUID.fromString(clientId));
        }
    }

But if you are using java 8 you can workaround the fact that lombok matches only the method name and not the entire signature when generating builder methods by using an interface with a default method.

package lombok.javac.handlers.stackoverflow;

import static org.junit.Assert.*;

import java.util.UUID;

import lombok.Builder;
import lombok.Value;

import org.junit.Test;

public class So33943193 {

    /**
     * The Interface WithClientUUID.
     *
     * @param <BLDR> the builder type
     */
    public static interface WithClientUUID<BLDR extends WithClientUUID<BLDR>> {

        /**
         * Client id.
         *
         * @param clientId the client id
         * @return the bldr
         */
        default BLDR clientId(String clientId) {
            return this.clientId(UUID.fromString(clientId));
        }

        /**
         * Client id.
         *
         * @param clientId the client id
         * @return the bldr
         */
        BLDR clientId(UUID clientId);

    }

    /**
     * The Class ClientApp.
     */
    @Builder(toBuilder = true)
    @Value
    public static class ClientApp {

        /** The client id. */
        private final UUID clientId;

        /**
         * Instantiates a new client app.
         *
         * @param clientId the client id
         */
        ClientApp(UUID clientId) {
            this.clientId = clientId;
        }

        /**
         * Implement the builder and extend the interface.
         */
        public static class ClientAppBuilder implements WithClientUUID<ClientAppBuilder> {}

    }

    /**
     * Test all scenarios
     */
    @Test
    public void testClientApp() {
        UUID expected = UUID.randomUUID();
        final ClientApp fromUuid = ClientApp.builder()
            .clientId(expected)
            .build();
        final ClientApp fromString = ClientApp.builder()
            .clientId(expected.toString())
            .build();
        assertEquals(expected, fromUuid.getClientId());
        assertEquals(expected, fromString.getClientId());

    }
}

Answer 2

Well, lombok will not generate this for you but you can use @Builder with and have a ClientAppBuilder class containing the one method that accepts a String and routes it to the other, to be generated, method. Possibly you need to mark your method with @Tolerate, otherwise Lombok will not generate the UUID accepting method.

Disclosure: I am a Lombok developer.