How to Format JSON in Java

Feb 01, 2026 3 min read

Java does not have a built-in JSON formatter, but the two most popular libraries, Jackson and Gson, both provide very easy ways to parse and pretty-print JSON data.

Example Code

Java

// Using Jackson (FasterXML)
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.JsonNode;

public class JsonFormatter {
    public static void main(String[] args) throws Exception {
        String jsonString = "{\"name\":\"John\",\"age\":30,\"city\":\"New York\"}";
        
        ObjectMapper mapper = new ObjectMapper();
        
        // Parse the JSON string
        Object jsonObject = mapper.readValue(jsonString, Object.class);
        
        // Pretty print it
        String formattedJson = mapper.writerWithDefaultPrettyPrinter()
                                     .writeValueAsString(jsonObject);
                                     
        System.out.println(formattedJson);
    }
}

Common Use Cases

Returning readable REST API JSON responses in frameworks like Spring Boot
Formatting and writing JSON to log files
Debugging deep, complex nested DTO objects

💡 Pro Tips for Java

Jackson writerWithDefaultPrettyPrinter() formats with spaces by default.
With Jackson, you can also inject ObjectWriter into Spring controllers.
Gson is lightweight, but Jackson offers better performance for large JSON datasets.

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