CODEWITHSUNDEEP
androidretrofit
Shane Doyle
Shane Doyle

Reputation: 1076

Handling Unauthorised Errors in Retrofit for Asynchronous Calls

I am using Retrofit for both asynchronous and synchronous api calls.

For both I have a custom error handler defined to handle unauthorised responses. For the synchronous calls I have declared the custom exception on the interface methods, I surround the interface implementation with a try/catch and it works perfect. I can catch Unauthorised Exceptions.

I have tried the same with asynchronous calls that use a callback and it doesn't work the same. Instead of the catching the Exception in the try/catch, I have to handle it in the failure method of the callback.

Here is the interface method:

@GET("getGardenGnomes")
void getGardenGnomes(@Header("Authorisation") String authorisation, Callback<GardenGnomes> callback) throws UnauthorisedException;

Here is the implementation:

void onClick() {
    try {
        getGardenGnomes()
    } catch (UnauthorisedException exception) {
        // .... handle the exception ....
    }
}

void getGardenGnomes() throws UnauthorisedException {
    // .... get client etc etc ....

    client.getGardenGnomes(authorisation, new Callback<GardenGnomes>() {
                @Override
                public void success(GardenGnomes gardenGnomes, Response response) {
                    // .... do something ....
                }

                @Override
                public void failure(RetrofitError error) {
                    // .... handle error ....
                }
            }
    );
}

The question is:

Should I just handle the exception in the failure(RetrofitError error) method of the Callback and don't declare throws UnauthorisedException on the interface method of asynchronous calls?

Or what is the best way to implement this?

Upvotes: 2

Views: 3794

Answers (1)

Miguel
Miguel

Reputation: 20153

The anwser is yes. Using Retrofit interfaces you don't declare which exception is thrown from the implementation on the interface. RetrofitError is a RuntimeException therefore unchecked. It's expected that a RetrofitError will be thrown on failures from the Retrofit implementation and you're responsible for handling it accordingly. Using synchronous method you simply use the try/catch as you mentioned. Using the asynchronous method you handle it in the failure callback method.

public void methodToHandleRetrofitError(RetrofitError error) {
    // handle the error
}

// Synchronous
try {
    client.getGardenGnomes(authorization)
} catch (RetrofitError e) {
    methodToHandleRetrofitError(e);
}

// Asynchronous
client.getGardenGnomes(authorisation, new Callback<GardenGnomes>() {
                @Override
                public void success(GardenGnomes gardenGnomes, Response response) {
                    // .... do something ....
                }

                @Override
                public void failure(RetrofitError error) {
                    methodToHandleRetrofitError(error);
                }
            }
    );

Hope this clarifies things for ya!

Upvotes: 11

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