Retrofit2 java.lang.NoClassDefFoundError: okhttp3/Call$Factory in JAVA

Question

I am not developing a Android Application ,
I'm just writing some JAVA codes to support Imgur API services.

public interface ImgurAPI {
    String server = "https://api.imgur.com";
    String BASE64 = "base64";

    @POST("/3/upload")
    void postImage(
            @Header("Authorization") String auth,
            @Query("title") String title,
            @Query("description") String description,
            @Query("type") String type,
            @Body String base64Image,
            Callback<ImageResponse> cb
    );

}

Main :

public static void main(String[] args) {

    try{
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl(ImgurAPI.server)
                .build();
        ImgurAPI myAPI = retrofit.create(ImgurAPI.class);
        String base64Image = new ImageReader(PATH).getBase64String();
        myAPI.postImage(AUTH, "Hi", "Test", ImgurAPI.BASE64, base64Image, new MyCallBack());

    }catch(Exception err){
        err.printStackTrace();
    }
}

and the exception throwing :

    Exception in thread "main" java.lang.NoClassDefFoundError: okhttp3/Call$Factory
    at Main.main(Main.java:14)

Caused by: java.lang.ClassNotFoundException: okhttp3.Call$Factory

I found out lots of solutions of Android. So I'm wondering if Retrofit available in only JAVA.
thanks .

Answer 1

I solved it , If you are writing Java (Only Java), And you downloaded the Jar of Retrofit2, It might not contain certain libraries which built-in in Android Studio, So you have to download them manually.

1. OkHttp3 OkHttp3 3.0.0 Jar download
2. Okio Okio 1.6.0 Jar download
3. Retrofit-converter gson Retrofit converter gson-2 beta3 Jar download (If you want to convert other types of data , just download other Jars in Retrofit )
4. Gson Gson 2.2.3 Jar download

Import the jar files , then It could work

Make sure you got all of its