How to convert hashmap to JSON object in Java

Question

How to convert or cast hashmap to JSON object in Java, and again convert JSON object to JSON string?

Answer 1

Underscore-java library can convert hash map or array list to json and vice verse.

import com.github.underscore.lodash.U;
import java.util.*;

public class Main {

    public static void main(String[] args) {

        Map map = new LinkedHashMap<>();
        map.put("1", "a");
        map.put("2", "b");

        System.out.println(U.toJson(map));
        // {
        //    "1": "a",
        //    "2": "b"
        // }
    }
}