How to convert complex Object to Json String - json

Question

I have following class defined:
public class ClassObjectTwo {
Long a;
Long b;
}
public class ClassObjectThree{
Long c;
Long d;
}
public class ClassObject{
private final ClassObjectTwo obj1;
private final ClassObjectTwo obj2;
private final ClassObjectTwo obj3;
private final Multimap<String, ClassObjectThree> obj4;
}
ClassObject classObj;
Gson gson = new Gson();
String jsonString = gson.toJson(classObj);
return jsonString;
JsonString is not returning anything, How to define Object of object to convert into JSON String ?
How to use InstanceCreator here ?

Answer 1

Not entirely sure, what the issue here is, when you say, it's not returning anything. Try making use of GsonBuilder.
you could use - GsonBuilder, and enable the complexMapKeySerialization as below.
Gson gson = new GsonBuilder().registerTypeAdapter(Instant.class, new InstantConverter()).enableComplexMapKeySerialization()
.setPrettyPrinting().create();
Since the Gson uses, toString() methods, for forming the JSON, make sure to use them.
public class ClassObject{
private final ClassObjectTwo obj1;
private final ClassObjectTwo obj2;
private final ClassObjectTwo obj3;
private final Multimap<String, ClassObjectThree> obj4;
#Override
public String toString() {
return new ToStringBuilder(this)
.append("obj1", obj1)
.append("obj2", obj2)
.append("obj3", obj3)
.append("obj4", obj4)
.toString();
}
}