How to Create a JSON File in Java — Jackson, Gson & JSON-P Examples

<!-- pom.xml -->
<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>2.15.2</version>
</dependency>

import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.File;
import java.util.*;

public class CreateJson {
    public static void main(String[] args) throws Exception {
        ObjectMapper mapper = new ObjectMapper();

        Map<String, Object> student = new LinkedHashMap<>();
        student.put("name", "Alice");
        student.put("age", 21);
        student.put("courses", List.of("Math", "CS"));

        mapper.writerWithDefaultPrettyPrinter()
              .writeValue(new File("student.json"), student);

        System.out.println("JSON file created.");
    }
}

import com.google.gson.*;
import java.io.*;

Gson gson = new GsonBuilder().setPrettyPrinting().create();
JsonObject obj = new JsonObject();
obj.addProperty("name", "Alice");
obj.addProperty("age", 21);

try (Writer writer = new FileWriter("student.json")) {
    gson.toJson(obj, writer);
}