JSON Processing in Java

JSON (JavaScript Object Notation) processing in Java involves parsing JSON data received from a web service or generating JSON data to send to a web service. Java provides several libraries for working with JSON, including `org.json`, Jackson, and Gson. Here's how you can parse and generate JSON data using these libraries:

Parsing JSON with `org.json`

import org.json.JSONArray;
import org.json.JSONObject;

public class JsonParsingExample {
    public static void main(String[] args) {

        // Sample JSON data
        String jsonString = "{\"name\": \"John\", \"age\": 30, \"city\": \"New York\"}";

        // Parse JSON string to JSONObject
        JSONObject jsonObject = new JSONObject(jsonString);

        // Access values
        String name = jsonObject.getString("name");
        int age = jsonObject.getInt("age");
        String city = jsonObject.getString("city");

        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
        System.out.println("City: " + city);
    }
}

Parsing JSON with Jackson

<!-- Maven Dependency -->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.12.4</version>
</dependency>



import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JacksonParsingExample {
    public static void main(String[] args) throws Exception {

        // Sample JSON data
        String jsonString = "{\"name\": \"John\", \"age\": 30, \"city\": \"New York\"}";

        // Parse JSON string to JsonNode
        ObjectMapper mapper = new ObjectMapper();
        JsonNode jsonNode = mapper.readTree(jsonString);

        // Access values
        String name = jsonNode.get("name").asText();
        int age = jsonNode.get("age").asInt();
        String city = jsonNode.get("city").asText();

        System.out.println("Name: " + name);

        System.out.println("Age: " + age);
        System.out.println("City: " + city);
    }
}

Parsing JSON with Gson

<!-- Maven Dependency -->
<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>2.8.8</version>
</dependency>

import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

public class GsonParsingExample {
    public static void main(String[] args) {

        // Sample JSON data
        String jsonString = "{\"name\": \"John\", \"age\": 30, \"city\": \"New York\"}";

        // Parse JSON string to JsonObject
        JsonObject jsonObject = JsonParser.parseString(jsonString).getAsJsonObject();

        // Access values
        String name = jsonObject.get("name").getAsString();
        int age = jsonObject.get("age").getAsInt();
        String city = jsonObject.get("city").getAsString();

        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
        System.out.println("City: " + city);
    }
}

Generating JSON with `org.json`

import org.json.JSONObject;

public class JsonGenerationExample {
    public static void main(String[] args) {

        // Create JSONObject
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("name", "John");
        jsonObject.put("age", 30);
        jsonObject.put("city", "New York");

        // Convert JSONObject to JSON string
        String jsonString = jsonObject.toString();

        System.out.println(jsonString);
    }
}

Generating JSON with Jackson

import com.fasterxml.jackson.databind.ObjectMapper;

public class JacksonGenerationExample {
    public static void main(String[] args) throws Exception {

        // Create ObjectMapper
        ObjectMapper mapper = new ObjectMapper();

        // Create JSON object
        Object jsonObject = mapper.createObjectNode()
                .put("name", "John")
                .put("age", 30)
                .put("city", "New York");

        // Convert JSON object to JSON string
        String jsonString = mapper.writeValueAsString(jsonObject);

        System.out.println(jsonString);
    }
}

Generating JSON with Gson

import com.google.gson.JsonObject;

public class GsonGenerationExample {
    public static void main(String[] args) {

        // Create JsonObject
        JsonObject jsonObject = new JsonObject();
        jsonObject.addProperty("name", "John");
        jsonObject.addProperty("age", 30);
        jsonObject.addProperty("city", "New York");

        // Convert JsonObject to JSON string
        String jsonString = jsonObject.toString();

        System.out.println(jsonString);
    }
}

Conclusion

JSON processing in Java involves parsing JSON data received from a web service or generating JSON data to send to a web service. Java provides several libraries for working with JSON, including `org.json`, Jackson, and Gson. By using these libraries, you can easily parse and generate JSON data in your Java applications.