Error Handling Example Real World

vavr_expressive_error_handling.java

interface CustomerProvider {
    List<String> getPersonalRecomendations(final String customerId) throws IOException,IllegalArgumentException;
}

interface GenericSuggestionProvider {
    List<String> getGeneralRecomendations() throws IOException;
}

interface CacheSuggestionProvider {
    List<String> getCachedRecomendations();
}

CustomerProvider customer;
GenericSuggestionProvider suggestion;
CacheSuggestionProvider cache;

public List<String> emptySuggestionList() {
    return new ArrayList<>();
}

List<String> getRecomendationsForUI(final String customerId) {
   return Try.of(() -> customer.getPersonalRecomendations(customerId))
                .orElse(() -> Try.of(() -> suggestion.getGeneralRecomendations()))
                .recover(IllegalArgumentException.class, cache.getCachedRecomendations())
                .recover(IOException.class, cache.getCachedRecomendations())
                .andFinally(System.out::println) // You can log metrics etc. here.
                .get();

}