Lombok @Builder and JPA Default constructor

Updated

Based on the feedback and John's answer I have updated the answer to no longer use @Tolerate or @Data and instead we create accessors and mutators via @Getter and @Setter, create the default constructor via @NoArgsConstructor, and finally we create the all args constructor that the builder requires via @AllArgsConstructor.

Since you want to use the builder pattern I imagine you want to restrict visibility of the constructor and mutators methods.To achieve this we set the visibility to package private via the access attribute on the @NoArgsConstructor and @AllArgsConstructor annotations and the value attribute on the @Setterannotation.

Important

Remember to properly override toString, equals, and hashCode.See the following posts by Vlad Mihalcea for details:

• the-best-way-to-implement-equals-hashcode-and-tostring-with-jpa-and-hibernate
• how-to-implement-equals-and-hashcode-using-the-jpa-entity-identifier
• hibernate-facts-equals-and-hashcode

package com.stackoverflow.SO34299054;import static org.junit.Assert.*;import java.util.Random;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import org.junit.Test;import lombok.AccessLevel;import lombok.AllArgsConstructor;import lombok.Builder;import lombok.Getter;import lombok.NoArgsConstructor;import lombok.Setter;@SuppressWarnings("javadoc")public class Answer {    @Entity    @Builder(toBuilder = true)    @AllArgsConstructor(access = AccessLevel.PACKAGE)    @NoArgsConstructor(access = AccessLevel.PACKAGE)    @Setter(value = AccessLevel.PACKAGE)    @Getter    public static class Person {        @Id        @GeneratedValue(strategy = GenerationType.AUTO)        private Long id;        /*         * IMPORTANT:         * Set toString, equals, and hashCode as described in these         * documents:         * - https://vladmihalcea.com/the-best-way-to-implement-equals-hashcode-and-tostring-with-jpa-and-hibernate/         * - https://vladmihalcea.com/how-to-implement-equals-and-hashcode-using-the-jpa-entity-identifier/         * - https://vladmihalcea.com/hibernate-facts-equals-and-hashcode/         */    }    /**     * Test person builder.     */    @Test    public void testPersonBuilder() {        final Long expectedId = new Random().nextLong();        final Person fromBuilder = Person.builder()            .id(expectedId)            .build();        assertEquals(expectedId, fromBuilder.getId());    }    /**     * Test person constructor.     */    @Test    public void testPersonConstructor() {        final Long expectedId = new Random().nextLong();        final Person fromNoArgConstructor = new Person();        fromNoArgConstructor.setId(expectedId);        assertEquals(expectedId, fromNoArgConstructor.getId());    }}

Old Version using @Tolerate and @Data:

Using @Tolerate worked to allow adding a noarg constructor.

Since you want to use the builder pattern I imagine you want to control visibility of the setter methods.

The @Data annotation makes the generated setters public, applying @Setter(value = AccessLevel.PROTECTED) to the fields makes them protected.

Remember to properly override toString, equals, and hashCode.See the following posts by Vlad Mihalcea for details:

• the-best-way-to-implement-equals-hashcode-and-tostring-with-jpa-and-hibernate
• how-to-implement-equals-and-hashcode-using-the-jpa-entity-identifier
• hibernate-facts-equals-and-hashcode

package lombok.javac.handlers.stackoverflow;import static org.junit.Assert.*;import java.util.Random;import javax.persistence.GenerationType;import javax.persistence.GeneratedValue;import javax.persistence.Id;import lombok.AccessLevel;import lombok.Builder;import lombok.Data;import lombok.Setter;import lombok.experimental.Tolerate;import org.junit.Test;public class So34241718 {    @Builder    @Data    public static class Person {        @Id        @GeneratedValue(strategy = GenerationType.AUTO)        @Setter(value = AccessLevel.PROTECTED)        Long id;        @Tolerate        Person() {}       /* IMPORTANT:          Override toString, equals, and hashCode as described in these           documents:          - https://vladmihalcea.com/the-best-way-to-implement-equals-hashcode-and-tostring-with-jpa-and-hibernate/          - https://vladmihalcea.com/how-to-implement-equals-and-hashcode-using-the-jpa-entity-identifier/          - https://vladmihalcea.com/hibernate-facts-equals-and-hashcode/          */    }    @Test    public void testPersonBuilder() {        Long expectedId = new Random().nextLong();        final Person fromBuilder = Person.builder()            .id(expectedId)            .build();        assertEquals(expectedId, fromBuilder.getId());    }    @Test    public void testPersonConstructor() {        Long expectedId = new Random().nextLong();        final Person fromNoArgConstructor = new Person();        fromNoArgConstructor .setId(expectedId);        assertEquals(expectedId, fromNoArgConstructor.getId());    }}

You can also solve it explicitly with @Data @Builder @NoArgsConstructor @AllArgsConstructor combined on the class definition.

It seems that the annotations order is important here, using the same annotations, but different orders, you can have the code working, or not.

Here is a non working example:

@AllArgsConstructor@Builder@Data@Entity@EqualsAndHashCode@NoArgsConstructor@RequiredArgsConstructor@Table@ToStringpublic class Person implements Serializable {  private String name;}

And this is a working example:

@Builder@Data@Entity@EqualsAndHashCode@AllArgsConstructor@NoArgsConstructor@RequiredArgsConstructor@Table@ToStringpublic class Person implements Serializable {  private String name;}

So be sure to have the @Builder annotation at the very top position, in my case I encountered this error because I wanted to sort annotations alphabetically.