How to handle different types of exceptions and errors in retrofit 2.0.1

Question

I am using Retrofit 2.0.1. I want to handle all types of network errors and exceptions (like no network connection ,timeout error,server not found etc.) I have found this link. But some of the methods were deprecated in v1.8.0. How can I do that in 2.0.1?

Answer 1

If you need centeralize error handler take a look at this thread But if you just need a simple error handler you can do:

 @Override
 public void onFailure(Throwable throwable) {
    if (throwable instanceof HttpException) {
       // We had non-2XX http error
    }
    if (throwable instanceof IOException) {
       // A network or conversion error happened
    }

    // We don't know what happened. We need to simply convert to an unknown error
    // ...
  }

Answer 2

Connection status should be checked anyway and has nothing to do with RetroFit, look up ConnectivityManager.

(a quicky solution is something like this, modify to your needs):

public boolean isConnected()
{
  ConnectivityManager manager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
  NetworkInfo info = manager.getActiveNetworkInfo();

  return (info != null && info.isConnected());
}

EDIT: Consider this - ConnectivityManager let's you know you have an interface for outgoing data, if you want to know if you actually have an outside link, I would suggest to ping you server (or any other known domian that would respond), if the ping is good, you have a line, for Timeouts and serverNotFound - use the http codes you get back in onFailure() for an api request (e.g. 404, 400, 200, etc.).

The Why

A ping is just a single udp packet that let's you know the server is there and alive, so a scenario where a ping works, but an http request will return Bad Request is very possible, and can be handled easily, the logic is up to you.

For the other stuff - all the info you need to implement the handling you want can be found in the callbacks.

this example uses ResponseBody, you can get the delivery info from the header:

@Override
public void onResponse(Call<ResponseBody> call, retrofit2.Response<ResponseBody> rawResponse)
{
  try
  {
   String response = rawResponse.headers().toString();
   //now print this...
  }
  catch(Exception e)
  {
   e.printStackTrace();
  }
}

Timeouts and serverNotFound can be handeled through the onFailure callback (this is the skeleton, implement what you need inside it, read up about it):

@Override
public void onFailure(Call<ResponseBody> call, Throwable throwable)
{
 //use throwable.get.... to know what happened
 throwable.printStackTrace();
}

Hope this helps in any way