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Asked: 2024-09-22T06:21:26+05:30

How can I transform JSON property names formatted in snake_case to Java’s camelCase style using Gson? I’m looking for a method or approach that can effectively handle this conversion when deserializing JSON data into Java objects. Any guidance or examples would be greatly appreciated.

Hey everyone! I’ve been working on a project where I need to deserialize some JSON data into Java objects using Gson, but I’ve hit a bit of a snag. The JSON property names are formatted in snake_case (like `first_name`, `last_name`), and I need to convert them to camelCase (like `firstName`, `lastName`) so they match my Java class fields.

I’m looking for an effective method or perhaps a custom approach to handle this transformation during the deserialization process. Has anyone here dealt with something similar? Any tips, code examples, or guidance on how to implement this conversion with Gson would be super helpful! Thanks in advance!

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    3 Answers



    1. Gson Snake Case to Camel Case Transformation

      Transforming Snake Case JSON to Camel Case in Gson

      Hey there! I totally understand the challenge you’re facing with deserializing JSON property names formatted in snake_case into Java objects that use camelCase. Fortunately, Gson provides a way to customize the naming strategy during the deserialization process.

      Here’s a simple approach using a custom FieldNamingStrategy to handle the conversion:

      import com.google.gson.FieldNamingStrategy;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import java.lang.reflect.Field;

public class SnakeCaseToCamelCaseStrategy implements FieldNamingStrategy {
    @Override
    public String translateName(Field field) {
        String name = field.getName();
        StringBuilder newName = new StringBuilder();
        boolean nextUpperCase = false;

        for (char ch : name.toCharArray()) {
            if (ch == '_') {
                nextUpperCase = true;
            } else {
                if (nextUpperCase) {
                    newName.append(Character.toUpperCase(ch));
                    nextUpperCase = false;
                } else {
                    newName.append(ch);
                }
            }
        }

        return newName.toString();
    }

    public static void main(String[] args) {
        Gson gson = new GsonBuilder()
                .setFieldNamingStrategy(new SnakeCaseToCamelCaseStrategy())
                .create();

        String json = "{\"first_name\":\"John\", \"last_name\":\"Doe\"}";
        Person person = gson.fromJson(json, Person.class);
        System.out.println(person.getFirstName() + " " + person.getLastName());
    }
}

class Person {
    private String firstName;
    private String lastName;

    public String getFirstName() {
        return firstName;
    }

    public String getLastName() {
        return lastName;
    }
}

      In this example:

      • We’ve created a SnakeCaseToCamelCaseStrategy class that implements FieldNamingStrategy.
      • The translateName method handles the conversion from snake_case to camelCase.
      • We build a Gson instance with this custom strategy and use it to deserialize the JSON data into a Person object.

      Simply replace the Person class with your own class structure, and this should work perfectly for your needs! Let me know if you have any further questions or need additional guidance!




    2. Gson JSON Deserialization

      Deserializing JSON with Gson: Snake_case to CamelCase

      Hey there!

      Welcome to the world of Java programming! It can be tricky at first, but I’m here to help you out with your Gson and JSON handling issue.

      When dealing with JSON that has snake_case property names and you want to map them to Java fields in camelCase, you can easily accomplish this by creating a custom ExclusionStrategy or using a JsonDeserializer. Here’s a basic approach using Gson’s @SerializedName annotation and by customizing the Gson instance.

      Option 1: Using @SerializedName

      If your Java class looks something like this:

          public class User {
        @SerializedName("first_name")
        private String firstName;
        
        @SerializedName("last_name")
        private String lastName;

        // Getters and setters...
    }

      This way, Gson will automatically match the JSON properties to your Java fields during deserialization!

      Option 2: Customizing Gson

      If you want to transform everything without modifying your Java class, you can achieve this with a custom deserializer:

          import com.google.gson.*;
    import java.lang.reflect.Type;

    public class UserDeserializer implements JsonDeserializer {
        @Override
        public User deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
            JsonObject jsonObject = json.getAsJsonObject();
            User user = new User();
            user.setFirstName(jsonObject.get("first_name").getAsString());
            user.setLastName(jsonObject.get("last_name").getAsString());
            return user;
        }
    }

    GsonBuilder gsonBuilder = new GsonBuilder();
    gsonBuilder.registerTypeAdapter(User.class, new UserDeserializer());
    Gson gson = gsonBuilder.create();

      Now you can use this customized Gson instance to deserialize your JSON!

      Example Usage

          String json = "{\"first_name\":\"John\", \"last_name\":\"Doe\"}";
    User user = gson.fromJson(json, User.class);

      And you should be all set! Hope this helps you get started with Gson and JSON deserialization. Don’t hesitate to ask if you have more questions!



    3. To handle the transformation from snake_case to camelCase during the deserialization process using Gson, you can create a custom `JsonDeserializer`. This way, you can define how Gson should convert your JSON strings into Java objects while applying the necessary naming convention transformations. Below is an example of how you might implement this. First, create a custom deserializer class that converts the snake_case properties in the JSON string to the appropriate camelCase properties in your Java class.

      Here is a sample code snippet to demonstrate this approach. Define your Java class, then create a `Deserializer` that uses regular expressions to substitute underscores followed by letters with their uppercase equivalents. Finally, register this deserializer with your Gson instance when reading the JSON data. This method ensures that you handle the naming convention transformations seamlessly while deserializing your JSON data into Java objects.


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