Java Typer Error Handling with Sealed Interfaces

Overview

This short demo showcases the use of Java sealed interfaces when implementing Typed Error Handling.

It's considered a bad practice to use checked / unchecked exceptions as ways to control the logical flow of an application. Modern Java language features like sealed interfaces and pattern matching provide a way to handle all expected logical branches of an app in a secure, performant and elegant way.

Exploring the demo

The repo consists of 3 branches:

• main uses exceptions to drive the application logic
• feature/refactor-with-sealed-classes shows a version that uses sealed interfaces
• feature/refactor-with-sealed-classes-and-optional shows a version that uses the now common return type of Optional<T> for the findByEmail repo method.

Additional Links

• Functional Error Handling with Java
• Intro to VAVR's Either type - a more generic approach of typed error handling