android - response retrofit 2

Android - response retrofit 2

Using Retrofit 2 to handle responses in Android involves creating a service interface, defining a data model, and making network calls. Here's a quick guide to help you set it up:

Step-by-Step Guide

  1. Add Retrofit Dependencies: In your build.gradle (app-level), add the following dependencies:

    implementation 'com.squareup.retrofit2:retrofit:2.9.0' implementation 'com.squareup.retrofit2:converter-gson:2.9.0' // For JSON conversion

  2. Create Data Model: Define a data model class that matches the structure of your JSON response.

    public class User { private String name; private String email; // Getters and setters public String getName() { return name; } public void setName(String name) { this.name = name; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } }

  3. Create Retrofit Interface: Define an interface for your API calls.

    import retrofit2.Call; import retrofit2.http.GET; public interface ApiService { @GET("users") Call<List<User>> getUsers(); }

  4. Set Up Retrofit Instance: Create a Retrofit instance in your application or activity.

    import retrofit2.Retrofit; import retrofit2.converter.gson.GsonConverterFactory; public class ApiClient { private static final String BASE_URL = "https://api.example.com/"; private static Retrofit retrofit = null; public static Retrofit getClient() { if (retrofit == null) { retrofit = new Retrofit.Builder() .baseUrl(BASE_URL) .addConverterFactory(GsonConverterFactory.create()) .build(); } return retrofit; } }

  5. Make API Call: Use the Retrofit instance to make an API call and handle the response.

    import retrofit2.Call; import retrofit2.Callback; import retrofit2.Response; public void fetchUsers() { ApiService apiService = ApiClient.getClient().create(ApiService.class); Call<List<User>> call = apiService.getUsers(); call.enqueue(new Callback<List<User>>() { @Override public void onResponse(Call<List<User>> call, Response<List<User>> response) { if (response.isSuccessful() && response.body() != null) { List<User> users = response.body(); // Handle the list of users } else { // Handle error } } @Override public void onFailure(Call<List<User>> call, Throwable t) { // Handle failure } }); }

Summary

  1. Dependencies: Add Retrofit and converter dependencies.
  2. Data Model: Create a model class to map JSON data.
  3. API Interface: Define endpoints in an interface.
  4. Retrofit Instance: Set up a Retrofit instance.
  5. Make Calls: Use the interface to make asynchronous calls and handle responses.

By following these steps, you can easily handle API responses using Retrofit 2 in your Android application.

Examples

  1. "How to handle API response in Retrofit 2?"

    Description: Use Retrofit's callback interface to handle API responses asynchronously.

    Code:

    Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.example.com/") .addConverterFactory(GsonConverterFactory.create()) .build(); ApiService apiService = retrofit.create(ApiService.class); Call<MyResponse> call = apiService.getData(); call.enqueue(new Callback<MyResponse>() { @Override public void onResponse(Call<MyResponse> call, Response<MyResponse> response) { if (response.isSuccessful()) { MyResponse data = response.body(); // Handle the successful response } } @Override public void onFailure(Call<MyResponse> call, Throwable t) { // Handle the failure } });

  2. "How to parse JSON response with Retrofit 2?"

    Description: Define a model class that matches the JSON structure for automatic parsing.

    Code:

    public class MyResponse { private String name; private int age; // Getters and setters }

  3. "How to handle error responses in Retrofit 2?"

    Description: Check the response code and handle errors appropriately in the onResponse method.

    Code:

    @Override public void onResponse(Call<MyResponse> call, Response<MyResponse> response) { if (response.isSuccessful()) { MyResponse data = response.body(); } else { // Handle error response Log.e("Error", "Error code: " + response.code()); } }

  4. "How to set up Retrofit 2 with Gson for response conversion?"

    Description: Use GsonConverterFactory to convert JSON responses to Java objects.

    Code:

    Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.example.com/") .addConverterFactory(GsonConverterFactory.create()) .build();

  5. "How to make a POST request with Retrofit 2?"

    Description: Use the @POST annotation to send data in a POST request.

    Code:

    @POST("endpoint") Call<MyResponse> createData(@Body MyRequest request);

  6. "How to handle different response types with Retrofit 2?"

    Description: Use generics to handle various response types.

    Code:

    Call<ResponseType> call = apiService.getData(); call.enqueue(new Callback<ResponseType>() { @Override public void onResponse(Call<ResponseType> call, Response<ResponseType> response) { // Handle response } });

  7. "How to add headers to Retrofit 2 requests?"

    Description: Use @Header annotation to add headers to requests.

    Code:

    @GET("endpoint") Call<MyResponse> getData(@Header("Authorization") String token);

  8. "How to use Retrofit 2 with RxJava for asynchronous calls?"

    Description: Integrate Retrofit with RxJava for reactive programming.

    Code:

    Call<MyResponse> call = apiService.getData(); call.subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(new Observer<MyResponse>() { @Override public void onNext(MyResponse response) { // Handle response } @Override public void onError(Throwable e) { // Handle error } });

  9. "How to handle Retrofit 2 timeouts?"

    Description: Set connection and read timeouts when building the Retrofit instance.

    Code:

    OkHttpClient client = new OkHttpClient.Builder() .connectTimeout(30, TimeUnit.SECONDS) .readTimeout(30, TimeUnit.SECONDS) .build(); Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.example.com/") .client(client) .addConverterFactory(GsonConverterFactory.create()) .build();

  10. "How to log Retrofit 2 responses?"

    Description: Use an interceptor to log request and response data for debugging.

    Code:

    HttpLoggingInterceptor logging = new HttpLoggingInterceptor(); logging.setLevel(HttpLoggingInterceptor.Level.BODY); OkHttpClient client = new OkHttpClient.Builder() .addInterceptor(logging) .build(); Retrofit retrofit = new Retrofit.Builder() .baseUrl("https://api.example.com/") .client(client) .addConverterFactory(GsonConverterFactory.create()) .build();

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