java

Main.java

import static java.lang.Thread.sleep;

public class Main {
    public static void main(String[] args) {
        try {
            Validation validation = validate();
            try {
                Value value = update_db(validation);
                send_email(value);
            } catch (DBError db) {
                try {
                    sleep(5);
                    Value value = update_db(validation);
                    send_email(value);
                } catch(InterruptedException ie) {
                    // do nothing, stupid java-ism
                } catch(DBError db2) {
                    try {
                        Value value = update_db_remote(validation);
                        send_email(value);
                    } catch (DBError db3) {
                        notify_user(db3);
                    } catch (EmailFailedError e) {
                        requeue_email(e);
                    }
                } catch (EmailFailedError e) {
                    requeue_email(e);
                }
            } catch (EmailFailedError e) {
                requeue_email(e);
            }
        } catch(ValidationError v) {
            notify_user(v);
        }
    }

    public static void requeue_email(EmailFailedError e) {
        // do something to requeue email
    }

    private static Validation validate() throws ValidationError {
        return new Validation("credentials");
    }

    private static Value update_db(Validation validation) throws DBError {
        return new Value(4);
    }

    private static Value update_db_remote(Validation validation) throws DBError {
        return new Value(5);
    }

    private static void send_email(Value value) throws EmailFailedError {
        System.out.println("Sending email");
    }

    private static void notify_user(ValidationError ve) {
        System.out.println("oh no an error");
    }

    private static void notify_user(DBError ve) {
        System.out.println("oh no an error 2");
    }

    private static class ValidationError extends Throwable {

    }

    private static class DBError extends Throwable {

    }

    private static class EmailFailedError extends Throwable {

    }

    private static class Validation {
        String str;

        public Validation(String str) {
            this.str = str;
        }
    }

    private static class Value {
        int my_val;
        public Value(int my_val) {
            this.my_val = my_val;
        }
    }
}