Retrofit Rxjava error handler - error-handling

Question

I have a service class which is used to call api requset
here is an example method:
public Observable<List<Category>> test(Location location, int radius) {
Observable<CategoryListResponse> observable = api.test();
return observable
.doOnNext(new Action1<CategoryListResponse>() {
#Override
public void call(CategoryListResponse categoryListResponse) {
//handle error
}
})
.flatMap(new Func1<CategoryListResponse, Observable<Category>>() {
#Override
public Observable<Category> call(CategoryListResponse categoryListResponse) {
return Observable.from(categoryListResponse.getCategories());
}
})
.map(new Func1<Category, Category>() {
#Override
public Category call(Category category) {
//do something...
return category;
}
})
.toList();
}
And subscribe() will be called in another class.
observable.subscribe(new Action1<List<Category>>() {
#Override
public void call(List<Category> categories) {
//on success
}
}, new Action1<Throwable>() {
#Override
public void call(Throwable throwable) {
//on error
}
});
I was thinking to do error handling in the doOnNext() before it is returned back. but how can I trigger onError()?

Answer 1

You should throw a runtime exception and control the exception in onError operator in case that happens
Observable<CategoryListResponse> observable = api.test();
return observable
.doOnNext(list -> {
try{
request(list);
catch(Exception e){
throw new RuntimeException(e);
}
}).onError(t->//Here you control your errors otherwise it will be passed to OnError callback in your subscriber)
.flatMap(item -> Observable.from(item.getCategories()))
.map(category-> category)
.toList();
}
Try to use lambdas, make your code much more clear and readable
You can see some RxJava examples here https://github.com/politrons/reactive