It works but doesn't pass tests...

Question about the task

Using JSON to convert from one class to another

Java Collections, Level 3, Lesson 5

Under discussion

Well, I think that it does what is should do... Can somebody give me a little hint what's wrong with it?

REQUIRED CONNECTED LIBRARIES: Jackson Core, Bind and Annotation 2.6.1

Two classes have the same fields, but they don't have a common superclass. Example, First and Second classes.
Implement the convertOneToAnother method, which should return an instance of the resultClassObject class, whose fields are equal to the fields in the one object.
Use an ObjectMapper object.
Everybody knows that classes have a JSON annotation where the property equals the class's name in lowercase letters.
For example, for the First class, its className="first"
The First and Second classes themselves are not tested — they are provided as test data.

Requirements:

The convertOneToAnother method should return an instance of the resultClassObject class, whose fields are equal to the fields of the one object.
An ObjectMapper object must be created in the convertOneToAnother method.
The convertOneToAnother method must be static.
The convertOneToAnother method must be public.

package com.codegym.task.task33.task3304; import com.fasterxml.jackson.annotation.JsonSubTypes; import com.fasterxml.jackson.annotation.JsonTypeInfo; import com.fasterxml.jackson.databind.ObjectMapper; import java.io.IOException; import java.io.StringReader; import java.io.StringWriter; /* Using JSON to convert from one class to another */ public class Solution { public static void main(String[] args) throws IOException { Second s = (Second) convertOneToAnother(new First(), Second.class); //System.out.println(s.getClass().getSimpleName()); First f = (First) convertOneToAnother(new Second(), First.class); //System.out.println(f.getClass().getSimpleName()); } public static Object convertOneToAnother(Object one, Class resultClassObject) throws IOException { ObjectMapper mapperRead = new ObjectMapper(); StringWriter writer = new StringWriter(); mapperRead.writeValue(writer, one); String input = writer.toString(); input = input.replace(one.getClass().getSimpleName().toLowerCase(), resultClassObject.getSimpleName().toLowerCase()); StringReader reader = new StringReader(input); return mapperRead.readValue(reader, resultClassObject); } @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "className") @JsonSubTypes(@JsonSubTypes.Type(value = First.class, name = "first")) public static class First { public int i; public String name; } @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "className") @JsonSubTypes(@JsonSubTypes.Type(value = Second.class, name = "second")) public static class Second { public int i; public String name; } }

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brus5

Level 41 , Dąbrowa Górnicza, Poland

30 September 2020, 15:23

Test passed with simpler code

public static Object convertOneToAnother(Object one, Class resultClassObject) throws IOException {
    ObjectMapper mapper = new ObjectMapper();
    return mapper.disable(MapperFeature.USE_ANNOTATIONS).convertValue(one, resultClassObject);
}

Yu-Ping Lin

Level 29

6 January 2020, 00:22

@Senned gave the correct way to solve this task. If you guys still stuck here, here is the code for you to reference

ObjectMapper mapper = new ObjectMapper();
StringWriter write = new StringWriter();
mapper.disable(MapperFeature.USE_ANNOTATIONS).writeValue(write, one);
return mapper.readValue(write.toString(), resultClassObject);

Senned

Level 41 , Azov, Russia

27 December 2019, 10:28

You need disable to using annotations - mapperRead.disable(MapperFeature.USE_ANNOTATIONS), and now we have objects with same fields and can use only one method of mapperRead for convertation.

Olek

Level 41 , Amsterdam, Netherlands

27 December 2019, 09:36

I am in the same boat. Tried 2 different solutions. But it doesn't pass the first test.