将改造添加到android项目中

Question

I want to try using Retrofit in a new Android project.

I have added the following to my build.gradle:

compile 'com.squareup.retrofit2:retrofit:2.3.0'
compile 'com.squareup.retrofit2:converter-gson:2.3.0'
compile 'com.google.code.gson:gson:2.8.0'

I have a POJO called 'Turbine' which looks as follows:

public class Turbine {
    String name;
}

I have my Endpoint service class:

import java.util.List;

import greenapps.objects.Turbine;
import retrofit2.Call;
import retrofit2.http.GET;
import retrofit2.http.Path;

    public interface GreenAppService {
        @GET("turbines/{id}")
        Call<List<Turbine>> turbine(@Path("id") String id);
    }

In my main activity in android I have the following code (this is where I want to execute the call and get back my Turbine pojo object filled with data from the backend:

import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
...
...
...
//Relevant snippet starts here
Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(Constants.API_V1_ENDPOINT)
            .build();

    GreenAppService service = retrofit.create(GreenAppService.class);
    Call<List<Turbine>> turbine = service.turbine("1");
    turbine.enqueue(new Callback<Turbine>() {
        @Override
        public void onResponse(Call<Turbine> call, Response<Turbine> response) {
            
        }

        @Override
        public void onFailure(Call<Turbine> call, Throwable t) {

        }
});//Relevant snippet ends here

On the turbine.enqueue line I am getting the following error:

I presume the syntax here is wrong somehow, but I don't quite see what is causing the issue.

Also, once this works, how do I get my Turbine object? Is it a case of doing Turbine t = response.body();

Answer 1

Because you defined that you are waiting an Array of Turbine.

turbine.enqueue(new Callback<Turbine>()

to

turbine.enqueue(new Callback<ArrayList<Turbine>>()

also you need to update onResponse and onFailure methods with arraylist.

I strongly suggest you to apply singleton pattern for your GreenAppService object.

UPDATE

Here is an example of singleton pattern.

public final class WebService {

   private static GreenAppService sInstance;

   public static GreenAppService getInstance() {
       if (sInstance == null) {
           sInstance = new Retrofit
           .Builder()
           .baseUrl(Constants.API_V1_ENDPOINT)
           .build();
       }

       return sInstance;
   }
}

After that we call like

WebService
    .getInstance()
    .yourmethod()
    .enqueue()

Answer 2

Easy way to add retrofit in your project with just one click. (one-time setup)

Retrofit zip

1. Extract the file and you will get the “Retrofit” folder inside.

2. Copy this folder following the Android Studio path Android\\Android Studio\\plugins\\android\\lib\\templates\\other

3. Restart your Android Studio.

4. Select your project in which you want to add retrofit and find an option below.

Project > New > Other> Retrofit

You can see full blog here

https://medium.com/@mestri.vinayak.n/quick-install-retrofit-in-your-android-project-custom-template-a14a6adc77c2