Retrofit builder client sample with implementation

APIRetroBuilder.java

import android.content.Context;

import java.util.concurrent.TimeUnit;

import okhttp3.OkHttpClient;
import okhttp3.logging.HttpLoggingInterceptor;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;

public class APIRetroBuilder {

    private static Retrofit OBJ_RETROFIT = null;
    private static String BASE_URL = "https://www.example.com/api/";

    public static Retrofit getRetroBuilder(Context context, boolean enableConnectTimeout) {

        if (OBJ_RETROFIT == null) {

            if (BuildConfig.BUILD_TYPE.equals(AppConstants.DEBUG_BUILD_TYPE)) {

                HttpLoggingInterceptor loggingInterceptor = new HttpLoggingInterceptor();
                loggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
                OkHttpClient.Builder clientBuilder = new OkHttpClient.Builder();
                clientBuilder.addInterceptor(loggingInterceptor); // print OkHTTP log
                if(enableConnectTimeout) {
                    clientBuilder.connectTimeout(2, TimeUnit.MINUTES);
                    clientBuilder.readTimeout(2, TimeUnit.MINUTES);
                }

                OBJ_RETROFIT = new Retrofit.Builder()
                        .baseUrl(BASE_URL)
                        .client(clientBuilder.build())
                        .addConverterFactory(GsonConverterFactory.create())
                        .build();
            } else {

                OBJ_RETROFIT = new Retrofit.Builder()
                        .baseUrl(BASE_URL)
                        .addConverterFactory(GsonConverterFactory.create())
                        .build();
            }
        }
        return OBJ_RETROFIT;
    }
}

APISample.java

public interface APISample {

    @GET("apiSampleList")
    Call<ModelResponse> callSampleListApi();
}

build.gradle

dependencies {
    ...
    implementation 'com.squareup.retrofit2:retrofit:2.5.0'
    implementation 'com.squareup.retrofit2:converter-gson:2.5.0'
    implementation 'com.squareup.okhttp3:okhttp:3.2.0'
    implementation 'com.squareup.okhttp3:logging-interceptor:3.3.1' // For print OkHTTP log
}

MainAcitivity.java

...
  
private void callGetSampleListAPI() {

        progressbar.setVisibility(View.VISIBLE);

        APISample objApiSample = APIRetroBuilder.getRetroBuilder(this, false).create(APISample.class);
        Call<ModelResponse> callModelSampleRes = objApiSample.callSampleListApi();
        callModelSampleRes.enqueue(new Callback<ModelResponse>() {
            @Override
            public void onResponse(Call<ModelResponse> call, Response<ModelResponse> response) {

                progressbar.setVisibility(View.GONE);
                try {
                    ModelResponse objModelRes = response.body();
                    if(objModelRes.getSuccess().equalsIgnoreCase("True")) {
                      // Update UI based on response
                    } else
                        Snackbar.make(mCrdntrlyot, objModelRes.getMessage(), Snackbar.LENGTH_LONG).show();
                } catch (Exception e) {
                    e.printStackTrace();
                    Snackbar.make(mCrdntrlyot, "There are some internal problem", Snackbar.LENGTH_LONG).show();
                }
            }

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

                progressbar.setVisibility(View.GONE);
                Snackbar.make(mCrdntrlyot, "There are some server problem", Snackbar.LENGTH_LONG).show();
            }
        });
    }
    
...