fasterxml serialize using toString and deserialize using String constructor

Through experimentation (I think the documentation could have been a little clearer on this) I have discovered that I can use the JsonCreator annotation on the String constructor and JsonValue on the toString() method to achieve what I want:

public class Thing{   private final int x;   private final int y;   private final int z;   @JsonCreator   public Thing(String strThing)   {       // parse strThing which is in some arbitrary format to set x, y and z   }   @Override   @JsonValue   public String toString()   {       // return a string representation of thing       // (same format as that parsed by the constructor)   }   @Override   public boolean equals(Object obj) ...   @Override   public int hashCode() ...}

you can make a new class which extends JsonSerializer and override its serialize method. Write your implementation which you were suppose to write inside toString() method, into JsonGenerator's writeString() method as shown. You will have to use jackson-core-asl.jar and jackson-mapper-asl.jar in your project. Below is JsonThingSerializer.java class

import java.io.IOException;import org.codehaus.jackson.JsonGenerator;import org.codehaus.jackson.JsonProcessingException;import org.codehaus.jackson.map.JsonSerializer;import org.codehaus.jackson.map.SerializerProvider;public class JsonThingSerializer extends JsonSerializer<Thing>{ //note use of generics@Overridepublic void serialize(Thing myThing, JsonGenerator gen,        SerializerProvider provider) throws IOException,        JsonProcessingException {    gen.writeString("I want this way.. which I was thinking to implement inside toString() method "+" "+myThing.getX()+" "+myThing.getY()+" "+myThing.getZ());}}

Use below annotations in your Thing.java

import org.codehaus.jackson.annotate.JsonAutoDetect;import org.codehaus.jackson.map.annotate.JsonSerialize;@JsonAutoDetect@JsonSerialize(using=JsonThingSerializer.class)public class Thing{   private final int x;   private final int y;   private final int z;   public Thing(String strThing)   {       // parse strThing which is in some arbitrary format to set x, y and z       //insert your own implementation to get x, y and z       x=y=z=10;   }   @Override   public String toString()   {       //no need to override this for json serialization.. mapper will not use it   }   @Override   public boolean equals(Object obj){     //you can have your own implementation   }   @Override   public int hashCode() {     //you can have your own implementation    }public int getX() {    return x;}public int getY() {    return y;}public int getZ() {    return z;}}

You can test your code using below code.

import java.io.IOException;import org.codehaus.jackson.JsonGenerationException;import org.codehaus.jackson.map.JsonMappingException;import org.codehaus.jackson.map.ObjectMapper;public class TestJsonSerialization {    public static void main(String[] args) {        Thing thing =new Thing("your strThing which is in some arbitrary format to set x, y and z");        ObjectMapper mapper =new ObjectMapper();        try {            String thingString = mapper.writeValueAsString(thing);            System.out.println(thingString);        } catch (JsonGenerationException e) {            e.printStackTrace();        } catch (JsonMappingException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }}

Blow is the output :

"I want this way.. which I was thinking to implement inside toString() method 10 10 10"