Java hashmap to json string

There are several ways to convert a Java HashMap to a JSON string. Here are two of the most common methods:

Using Gson

Gson is a popular Java library for converting Java objects to and from JSON. To convert a HashMap to a JSON string using Gson, you can use the following code:

import com.google.gson.Gson;

public class Main {

  public static void main(String[] args) {
    // Create a HashMap.
    HashMap<String, String> map = new HashMap<>();
    map.put("name", "John Doe");
    map.put("age", "30");

    // Create a Gson object.
    Gson gson = new Gson();

    // Convert the HashMap to a JSON string.
    String json = gson.toJson(map);

    // Print the JSON string.
    System.out.println(json);
  }
}

The output of the above code will be the following JSON string:

{
  "name": "John Doe",
  "age": "30"
}

Using Jackson

Jackson is another popular Java library for converting Java objects to and from JSON. To convert a HashMap to a JSON string using Jackson, you can use the following code:

import com.fasterxml.jackson.databind.ObjectMapper;

public class Main {

  public static void main(String[] args) {
    // Create a HashMap.
    HashMap<String, String> map = new HashMap<>();
    map.put("name", "John Doe");
    map.put("age", "30");

    // Create an ObjectMapper object.
    ObjectMapper mapper = new ObjectMapper();

    // Convert the HashMap to a JSON string.
    try {
      String json = mapper.writeValueAsString(map);
    } catch (JsonProcessingException e) {
      e.printStackTrace();
    }

    // Print the JSON string.
    System.out.println(json);
  }
}

The output of the above code will be the same as the output of the previous code.