CODEWITHSUNDEEP
javajsonjackson
Macarena
Macarena

Reputation: 123

Is there a way to serialise Java TreeMap into a JSON?

I have a Java TreeMap frutitas inside a custom object on the server side which I want to send to the frontend.

I use javax.ws and jackson to serialise. The data that I get in the frontend looks like this:

{ "frutitas": {
    "entry": [
        {
            "key": "fruto 1",
            "value": "el banano"
        },
        {
            "key": "fruto 2",
            "value": "el pineapple"
        }
    ]
}

But I want to get something like this, which is actually how I send the "frutitas" map inside the object that I send to the backend when I want to upload it:

{ 
    "frutitas": {
        "fruto 1": "el banano",
        "fruto 2": "el pineapple"
    }
}

Upvotes: 1

Views: 3561

Answers (3)

TechFree
TechFree

Reputation: 2964

Another option is to use gson.

<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>2.8.5</version>
</dependency>

And the class containing the map:

public class FrutitasClass {   
   private Map<String, String> frutitas; 
}

The code below would the conversion: 

Gson gson = new GsonBuilder().setPrettyPrinting().create();
String json = gson.toJson(frutitasClassObject);

Out:

{
  "frutitas": {
    "fruto 1": "el banano",
    "fruto 2": "el pineapple"
  }
}

Upvotes: 2

Michael Gantman
Michael Gantman

Reputation: 7788

Library Json-Jackson also known as FasterXML is de-facto standard for JSON serialization-deserialization. It works fast and is widely used. Below is a simple class that I wrote for serializing/de-serializing any Object. But in general you need to look at ObjectMapper class to see how it works. Here is Github link to a project. Here are Maven dependencies you may use:

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.9.9</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-jsr310</artifactId>
    <version>2.9.9</version>
</dependency>

My Class Example

package com.bla.json.utils;

import java.io.IOException;

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectReader;
import com.fasterxml.jackson.databind.ObjectWriter;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;


public class JsonUtil {

    private static final ObjectReader objectReader;
    private static final ObjectWriter objectWriter;

    static {
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.registerModules(new JavaTimeModule());
        objectMapper.enableDefaultTyping();
        objectReader = objectMapper.reader();
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        objectWriter = objectMapper.writer();
    }

    public static String writeObjectToJsonString(Object object) throws JsonProcessingException {
        String jsonData = null;
        if (object != null) {
            jsonData = objectWriter.writeValueAsString(object);
        }
        return jsonData;
    }

    public static <T> T readObjectFromJsonString(String s, Class<T> type) throws IOException {
        T data = objectReader.forType(type).readValue(s);
        return data;
    }
}

Upvotes: 1

Rowi
Rowi

Reputation: 565

You can convert TreeMap to JSONObject as you expected. Here is the sample so that you can get the idea.

JSONObject jsonObject = new JSONObject(yourTreeMap);

If you print jsonObject, Output will be like this.

{"fruto 1":"el banan","fruto 2":"el pineapple"}


JSONObject main = new JSONObject();
main.put("frutitas", jsonObject);

{ 
    "frutitas": {
        "fruto 1": "el banano",
        "fruto 2": "el pineapple"
    }
}

Upvotes: 1

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