Detect offline error in Retrofit

We will need to handle and detect the offline error in Retrofit call, It is a basic requirement when we are implementing Offline Application or visible network error view.

How can it be possible?

Essentially, we will create a class that implements Interceptor so that we can perform a network connectivity and checks before executing the request.

public class NetworkConnectionInterceptor implements Interceptor {
 
    private Context mContext;
 
    public NetworkConnectionInterceptor(Context context) {
        mContext = context;
    }
 
    @Override
    public Response intercept(Chain chain) throws IOException {
        if (!isOnline()) {
            throw new NoConnectivityException();
        }
 
        Request.Builder builder = chain.request().newBuilder();
        return chain.proceed(builder.build());
    }
   public boolean isOnline(){
      ConnectivityManager connectivityManager = (ConnectivityManager) mContext.getSystemService(Context.CONNECTIVITY_SERVICE);
      NetworkInfo netInfo = connectivityManager.getActiveNetworkInfo();
      return (netInfo != null && netInfo.isConnected());
   }
}

public class NetworkConnectionInterceptor implements Interceptor {

private Context mContext;

public NetworkConnectionInterceptor(Context context) {

mContext = context;

}

@Override

public Response intercept(Chain chain) throws IOException {

if (!isOnline()) {

throw new NoConnectivityException();

}

Request.Builder builder = chain.request().newBuilder();

return chain.proceed(builder.build());

}

public boolean isOnline(){

ConnectivityManager connectivityManager = (ConnectivityManager) mContext.getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo netInfo = connectivityManager.getActiveNetworkInfo();

return (netInfo != null && netInfo.isConnected());

}

NetworkConnectionInterceptor interceptor will handle every API call, when, if no network is found then it interrupts the normal flow of execution so we will create our own NoConnectivityException Exception class. that throws an Exception.

public class NoConnectivityException extends IOException {
 
    @Override
    public String getMessage() {
        return "Network Connection exception";
    }
 
}

public class NoConnectivityException extends IOException {

@Override

public String getMessage() {

return "Network Connection exception";

}

Add NetworkConnectionInterceptor with our retrofit Service client.

public class RetrofitClient {
    private static Retrofit retrofit = null;

    public static Retrofit getClient(Context mContext) {
        if (retrofit == null) {
            CookieManager cookieManager = new CookieManager();
            cookieManager.setCookiePolicy(CookiePolicy.ACCEPT_ALL);

            HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
            logging.setLevel(HttpLoggingInterceptor.Level.BODY);
            OkHttpClient.Builder oktHttpClient = new OkHttpClient.Builder()
                    .connectTimeout(DEFAULT_CONNECT_TIMEOUT_IN_MIN, TimeUnit.MINUTES)
                    .writeTimeout(DEFAULT_WRITE_TIMEOUT_IN_MIN, TimeUnit.MINUTES)
                    .readTimeout(DEFAULT_READ_TIMEOUT_IN_MIN, TimeUnit.MINUTES)
                    .addInterceptor(new NetworkConnectionInterceptor(mContext))
                    .cookieJar(new JavaNetCookieJar(cookieManager));

            oktHttpClient.addInterceptor(logging);

            retrofit = new Retrofit.Builder()
                    .baseUrl(BASE_URL)
                    .addConverterFactory(GsonConverterFactory.create())
                    .client(oktHttpClient.build())
                    .build();

        }
        return retrofit;
    }
}

public class RetrofitClient {

private static Retrofit retrofit = null;

public static Retrofit getClient(Context mContext) {

if (retrofit == null) {

CookieManager cookieManager = new CookieManager();

cookieManager.setCookiePolicy(CookiePolicy.ACCEPT_ALL);

HttpLoggingInterceptor logging = new HttpLoggingInterceptor();

logging.setLevel(HttpLoggingInterceptor.Level.BODY);

OkHttpClient.Builder oktHttpClient = new OkHttpClient.Builder()

.connectTimeout(DEFAULT_CONNECT_TIMEOUT_IN_MIN, TimeUnit.MINUTES)

.writeTimeout(DEFAULT_WRITE_TIMEOUT_IN_MIN, TimeUnit.MINUTES)

.readTimeout(DEFAULT_READ_TIMEOUT_IN_MIN, TimeUnit.MINUTES)

.addInterceptor(new NetworkConnectionInterceptor(mContext))

.cookieJar(new JavaNetCookieJar(cookieManager));

oktHttpClient.addInterceptor(logging);

retrofit = new Retrofit.Builder()

.baseUrl(BASE_URL)

.addConverterFactory(GsonConverterFactory.create())

.client(oktHttpClient.build())

.build();

}

return retrofit;

}

Finally, Detect Offline connection Exception in our Activity, Handler or Fragment.

 @Override
    public void onFailure(Call<BaseModel> call, Throwable t) {
        Log.d(TAG, "onResponse: 3");
        if(t instanceof NoConnectivityException) {
            t.printStackTrace();
            returnResponseFromOffLineDB((Activity) mContext);
        }
    }

@Override

public void onFailure(Call<BaseModel> call, Throwable t) {

Log.d(TAG, "onResponse: 3");

if(t instanceof NoConnectivityException) {

t.printStackTrace();

returnResponseFromOffLineDB((Activity) mContext);

}

ashwini gupta 18 August 2017

. . .

2 comments

heymonheymon Jan 3, 2019 at 8:12 pm

where exactly to put onFailure?

ashwini gupta (Moderator) Jan 3, 2019 at 8:29 pm
onFailure => It is a method of Retrofit Callback Interface and you detect your custom offline exception and do whatever you want. I am getting information from our database.

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Detect offline error in Retrofit

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