java - Can't make Jackson and Lombok work together

Question

I am experimenting in combining Jackson and Lombok. Those are my classes:

package testelombok;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import lombok.AllArgsConstructor;
import lombok.Value;
import lombok.experimental.Wither;

@Value
@Wither
@AllArgsConstructor(onConstructor=@__(@JsonCreator))
public class TestFoo {
    @JsonProperty("xoom")
    private String x;
    private int z;
}

package testelombok;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.xebia.jacksonlombok.JacksonLombokAnnotationIntrospector;
import java.io.IOException;

public class TestLombok {

    public static void main(String[] args) throws IOException {
        TestFoo tf = new TestFoo("a", 5);
        System.out.println(tf.withX("b"));
        ObjectMapper om = new ObjectMapper().setAnnotationIntrospector(new JacksonLombokAnnotationIntrospector());
        System.out.println(om.writeValueAsString(tf));
        TestFoo tf2 = om.readValue(om.writeValueAsString(tf), TestFoo.class);
        System.out.println(tf2);
    }

}

Those are the JARs that I'm adding into the classpth:

• Lombok: https://projectlombok.org/downloads/lombok.jar (version 1.16.10)

• Jackson annotations: http://repo1.maven.org/maven2/com/fasterxml/jackson/core/jackson-annotations/2.8.2/jackson-annotations-2.8.2.jar

• Jackson core: http://repo1.maven.org/maven2/com/fasterxml/jackson/core/jackson-core/2.8.2/jackson-core-2.8.2.jar

• Jackson databind: http://repo1.maven.org/maven2/com/fasterxml/jackson/core/jackson-databind/2.8.2/jackson-databind-2.8.2.jar

• Jackson-lombok: http://repo1.maven.org/maven2/io/paradoxical/jackson-lombok/1.1/jackson-lombok-1.1.jar

I am compiling it with Netbeans (I don't think that this is really relevant, but I am reporting this anyway to make it perfectly and faithfully reproducible). The five JARs above are kept in a folder called "lib" inside the project folder (along with "src", "nbproject", "test" and "build"). I added them to Netbeans via the "Add JAR/Folder" button in the project properties and they are listed in the exact order as the list above. The project is a standard "Java application" type project.

Further, the Netbeans project is configured to "do NOT compile on save", "generate debugging info", "report deprecated APIs", "track java dependencies", "activacte annotation proccessing" and "activacte annotation proccessing in the editor". No annotation processor or annotation processing option is explicitly configured in Netbeans. Also, the "-Xlint:all" command line option is passed in the compiler command line, and the compiler runs on an external VM.

My javac's version is 1.8.0_72 and my java's version is 1.8.0_72-b15. My Netbeans is 8.1.

My project compiles fine. However, it throws an exception in its execution. The exception don't seems to be anything that looks easily or obvious fixable. Here is the output, including the stacktrace:

TestFoo(x=b, z=5)
{"z":5,"xoom":"a"}
Exception in thread "main" com.fasterxml.jackson.databind.JsonMappingException: Argument #0 of constructor [constructor for testelombok.TestFoo, annotations: {interface java.beans.ConstructorProperties=@java.beans.ConstructorProperties(value=[x, z]), interface com.fasterxml.jackson.annotation.JsonCreator=@com.fasterxml.jackson.annotation.JsonCreator(mode=DEFAULT)}] has no property name annotation; must have name when multiple-parameter constructor annotated as Creator
 at [Source: {"z":5,"xoom":"a"}; line: 1, column: 1]
    at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:296)
    at com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCache2(DeserializerCache.java:269)
    at com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCacheValueDeserializer(DeserializerCache.java:244)
    at com.fasterxml.jackson.databind.deser.DeserializerCache.findValueDeserializer(DeserializerCache.java:142)
    at com.fasterxml.jackson.databind.DeserializationContext.findRootValueDeserializer(DeserializationContext.java:475)
    at com.fasterxml.jackson.databind.ObjectMapper._findRootDeserializer(ObjectMapper.java:3890)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3785)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2833)
    at testelombok.TestLombok.main(TestLombok.java:14)
Caused by: java.lang.IllegalArgumentException: Argument #0 of constructor [constructor for testelombok.TestFoo, annotations: {interface java.beans.ConstructorProperties=@java.beans.ConstructorProperties(value=[x, z]), interface com.fasterxml.jackson.annotation.JsonCreator=@com.fasterxml.jackson.annotation.JsonCreator(mode=DEFAULT)}] has no property name annotation; must have name when multiple-parameter constructor annotated as Creator
    at com.fasterxml.jackson.databind.deser.BasicDeserializerFactory._addDeserializerConstructors(BasicDeserializerFactory.java:511)
    at com.fasterxml.jackson.databind.deser.BasicDeserializerFactory._constructDefaultValueInstantiator(BasicDeserializerFactory.java:323)
    at com.fasterxml.jackson.databind.deser.BasicDeserializerFactory.findValueInstantiator(BasicDeserializerFactory.java:253)
    at com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.buildBeanDeserializer(BeanDeserializerFactory.java:219)
    at com.fasterxml.jackson.databind.deser.BeanDeserializerFactory.createBeanDeserializer(BeanDeserializerFactory.java:141)
    at com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer2(DeserializerCache.java:406)
    at com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer(DeserializerCache.java:352)
    at com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCache2(DeserializerCache.java:264)
    ... 7 more

I already tried about randomly poking with the @Value and @AllArgsConstructor annotations, but I couldn't make it any better.

I google'd the exception and found an old bug report on jackson, and another one that is open, but seems to be related to something else. However, this still do not tells anything about what is this bug or how to fix it. Also, I could not find anything useful looking that somewhere else.

Since what I am trying to do is very basic usage of both lombok and jackson, it seems odd that I couldn't find any more useful information about how to workaround this issue. Maybe I missed something?

Other than just saying "don't use lombok" or "don't use jackson", do anybody has any idea about how to solve this?

Answer 1

If you want immutable but a json serializable POJO using lombok and jackson. Use jacksons new annotation on your lomboks builder @JsonPOJOBuilder(withPrefix = "") I tried this solution and it works very well. Sample usage

import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.annotation.JsonPOJOBuilder;
import lombok.Builder;
import lombok.Value;

@JsonDeserialize(builder = Detail.DetailBuilder.class)
@Value
@Builder
public class Detail {

    private String url;
    private String userName;
    private String password;
    private String scope;

    @JsonPOJOBuilder(withPrefix = "")
    public static class DetailBuilder {

    }
}

If you have too many classes with @Builder and you want don't want the boilerplate code empty annotation you can override the annotation interceptor to have empty withPrefix

mapper.setAnnotationIntrospector(new JacksonAnnotationIntrospector() {
        @Override
        public JsonPOJOBuilder.Value findPOJOBuilderConfig(AnnotatedClass ac) {
            if (ac.hasAnnotation(JsonPOJOBuilder.class)) {//If no annotation present use default as empty prefix
                return super.findPOJOBuilderConfig(ac);
            }
            return new JsonPOJOBuilder.Value("build", "");
        }
    });

And you can remove the empty builder class with @JsonPOJOBuilder annotation.