Adding header to all request with Retrofit 2

Question

Retrofit 2\'s documentation says:

Headers that need to be added to every request can be specified using an OkHttp interceptor.

I

Answer 1

The Latest Retrofit Version HERE -> 2.1.0.

lambda version:

  builder.addInterceptor(chain -> {
    Request request = chain.request().newBuilder().addHeader("key", "value").build();
    return chain.proceed(request);
  });

ugly long version:

  builder.addInterceptor(new Interceptor() {
    @Override public Response intercept(Chain chain) throws IOException {
      Request request = chain.request().newBuilder().addHeader("key", "value").build();
      return chain.proceed(request);
    }
  });

full version:

class Factory {

public static APIService create(Context context) {

  OkHttpClient.Builder builder = new OkHttpClient().newBuilder();
  builder.readTimeout(10, TimeUnit.SECONDS);
  builder.connectTimeout(5, TimeUnit.SECONDS);

  if (BuildConfig.DEBUG) {
    HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
    interceptor.setLevel(HttpLoggingInterceptor.Level.BASIC);
    builder.addInterceptor(interceptor);
  }

  builder.addInterceptor(chain -> {
    Request request = chain.request().newBuilder().addHeader("key", "value").build();
    return chain.proceed(request);
  });

  builder.addInterceptor(new UnauthorisedInterceptor(context));
  OkHttpClient client = builder.build();

  Retrofit retrofit =
      new Retrofit.Builder().baseUrl(APIService.ENDPOINT).client(client).addConverterFactory(GsonConverterFactory.create()).addCallAdapterFactory(RxJavaCallAdapterFactory.create()).build();

  return retrofit.create(APIService.class);
  }
}

gradle file (you need to add the logging interceptor if you plan to use it):

  //----- Retrofit
  compile 'com.squareup.retrofit2:retrofit:2.1.0'
  compile "com.squareup.retrofit2:converter-gson:2.1.0"
  compile "com.squareup.retrofit2:adapter-rxjava:2.1.0"
  compile 'com.squareup.okhttp3:logging-interceptor:3.4.0'