How to Convert a Map to a JSON String in Java - Step by Step Examples

How to Convert a Map to a JSON String in Java ?

Answer

To convert a map to a JSON string in Java, you can use the Jackson library. This library provides an easy way to convert a Java Map to a JSON string.

✐ Examples

1 Converting a Map to a JSON String

We can convert a map to a JSON string in Java using the Jackson library's ObjectMapper class.

For example,

We start by adding the Jackson library to our project dependencies. If using Maven, include the Jackson dependency in your pom.xml.
We declare and initialize a map named myMap with key-value pairs.
We create an instance of the ObjectMapper class.
We convert the map to a JSON string using the writeValueAsString method of the ObjectMapper instance.
We print the resulting JSON string to the console using System.out.println.

Java Program

import com.fasterxml.jackson.databind.ObjectMapper;
import java.util.HashMap;
import java.util.Map;

public class Main {
    public static void main(String[] args) {
        // Declare and initialize a map
        Map<Integer, Integer> myMap = new HashMap<>();
        myMap.put(1, 10);
        myMap.put(2, 20);
        myMap.put(3, 30);
        myMap.put(4, 40);
        myMap.put(5, 50);

        // Create an ObjectMapper instance
        ObjectMapper objectMapper = new ObjectMapper();

        try {
            // Convert the map to a JSON string
            String jsonString = objectMapper.writeValueAsString(myMap);

            // Print the resulting JSON string
            System.out.println("JSON string from map: " + jsonString);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Output

JSON string from map: {"1":10,"2":20,"3":30,"4":40,"5":50}

Summary

In this tutorial, we learned How to Convert a Map to a JSON String in Java language with well detailed examples.

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