zappee zappee - 25 days ago 6
Java Question

Exception handling with Retrofit2

I am learning how to use

but I am in trouble.

Is that any way to catch the
object on
and throw an exception if the HTTP response code is out of the range 2xx?

I am implementing some JAX-RS rest services where my rest methods call another rest APIs to collect information and I would like to handle any HTTP error on the JAX-RS side:

public class HelloRest {

public String ping() throws IOException {
HelloService client = HelloServiceBuilder.getInstance();
String response = client.sayHello().execute().body();;

@GET ("echo/{msg}")
public String echo(@PathParam("msg") String msg) throws IOException {
HelloService client = HelloServiceBuilder.getInstance();
String response = client.echo(msg).execute().body();;
return response;

First, I have realized that the
method throws IOException so I had to add it to the rest methods signatures. That is okay, I can handle it properly with JAX-RS.

But what is the best way to handle errors which is related to HTTP responses where the response code is out of the range 2xx?

I do not want to write repeated code block to check the HTTP response code any time when I use Retrofit2 like this:

Response<String> response =;
int responseCode = response.code();
if (responseCode < 200 && responseCode > 299) {
throws AnyException("...");

String serverResponse = response.body();

Can I add something to the
code block to handle this situation on a general way somehow?

public final class HelloServiceBuilder {

private static final String SERVICE_URL = "...";

private HelloServiceBuilder() {
// do nothing

public static HelloService getInstance() {
Retrofit retrofit = new Retrofit.Builder()

return retrofit.create(HelloService.class);

Answer Source

Am going to create my rest client class with JAX-RS. It is part of Java, I do not need to add extra dependency to my pom, works like a charm and I need to create only one class instead of 2 or more:

public final class MyRestClient {
    private static Client client = ClientBuilder.newClient();

    public static String hello() {
        String serviceUrl = "http://..../";
        String path ="hello";

        Response response = client

        if (response.getStatus() == Response.Status.OK.getStatusCode()) {
            return response.getEntity(String.class);

        throw new WebApplicationException(response);