List with IDs between Dart & Java

To send List of IDs – a List<UUID> (orList<String> in Dart format) – to a Java Spring Boot backend as a @RequestBody, using Dart with Retrofit annotations, you can proceed like this:

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✅ Spring Boot Backend (Example)

Your controller might look like:

@PostMapping("/uuids")
public ResponseEntity<Void> receiveUuids(@RequestBody List<UUID> uuids) {
    System.out.println("Received UUIDs: " + uuids);
    return ResponseEntity.ok().build();
}

Spring will automatically convert the incoming JSON array of UUID strings to a List<UUID>.

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✅ Dart Retrofit Setup

Here’s how to send it using Retrofit in Dart:

1. Retrofit Interface

import 'package:retrofit/retrofit.dart';
import 'package:dio/dio.dart';

part 'your_api_client.g.dart';

@RestApi(baseUrl: "http://your.api.url")
abstract class YourApiClient {
  factory YourApiClient(Dio dio, {String baseUrl}) = _YourApiClient;

  @POST("/uuids")
  Future<void> sendUuids(@Body() List<String> uuids);
}

2. Sending UUIDs

final dio = Dio();
final client = YourApiClient(dio);

final uuidList = [
  "550e8400-e29b-41d4-a716-446655440000",
  "123e4567-e89b-12d3-a456-426614174000"
];

await client.sendUuids(uuidList);

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✅ Notes

• Dart UUIDs are typically handled as strings when serializing to JSON.
• If you’re using the uuid package in Dart, just use .toString() to get valid string representations.
• Ensure your Content-Type header is application/json (Dio does this by default).

How to do this manually: Ensure your Content-Type header is application/json (Dio does this by default).

 

✅ Best Way to Set Content-Type: application/json in Dart Retrofit

Since Dio handles application/json automatically when using @Body() with JSON-serializable types (like List<String>), you usually don’t need to set it.

However, to do it manually, here are your options:

---

✅ Option 1: Set globally on Dio

final dio = Dio(BaseOptions(
  baseUrl: "http://your.api.url",
  headers: {
    "Content-Type": "application/json",
  },
));

final client = YourApiClient(dio);

---

✅ Option 2: Set dynamically with @Header()

If you want to control it per call:

Retrofit API definition:

@POST("/uuids")
Future<void> sendUuids(
  @Header("Content-Type") String contentType,
  @Body() List<String> uuids,
);

Calling it:

await client.sendUuids("application/json", uuidList);

---

✅ Option 3: Dio interceptor (for advanced control)

You can also use an interceptor to force application/json if needed for all or specific requests.

dio.interceptors.add(InterceptorsWrapper(
  onRequest: (options, handler) {
    options.headers["Content-Type"] = "application/json";
    return handler.next(options);
  },
));

Here is more about Universal IDs in Flutter : https://programtom.com/dev/2023/07/13/what-flutter-packages-what-could-i-use-for-unique-device-identifier/