Guided: Handle and Log Exceptions in a Java App

Table of Contents

1. Challenge

   Introduction

   Welcome to this Code Lab on handling and logging exceptions in Java!

   In this lab, you'll work on a simple command-line banking application. The starting code is functional but brittle—it crashes easily and provides no useful diagnostic information when things go wrong.

   Your job is to transform this fragile code into a robust application by implementing professional-grade exception handling and logging. You will learn to catch and handle errors gracefully, define your own custom exceptions for business-specific problems, and integrate a powerful logging framework to record application events and errors.

   Let's get started!

   info > This lab experience was developed by the Pluralsight team using Forge, an internally developed AI tool utilizing Gemini technology. All sections were verified by human experts for accuracy prior to publication. For issue reporting, please contact us.

2. Challenge

   Step 2: Implementing Basic Exception Handling

   The foundation of robust error handling in Java is the try-catch-finally construct. This allows you to 'try' code that might fail, 'catch' specific exceptions if they occur, and run 'finally' cleanup code regardless of the outcome.

   We'll start by making our application resilient to bad user input.

3. Challenge

   Step 3: Creating and Throwing Custom Exceptions

   While Java provides many built-in exceptions, they are often too generic for application-specific errors. Creating your own custom exceptions makes your code's intent clearer and allows for more specific error handling.

   In this step, you'll define exceptions that represent violations of our bank's business rules.

4. Challenge

   Step 4: Catching Custom Exceptions

   Once your service layer is throwing custom exceptions, the client code needs to be updated to catch them. This allows the application to respond differently to different types of errors, such as providing a specific message to the user for an invalid withdrawal.

5. Challenge

   Step 5: Integrating a Logging Framework

   Printing to the console is fine for simple scripts, but real applications need a more powerful logging solution. A logging framework gives you control over log levels (INFO, DEBUG, ERROR), formatting, and where logs are sent.

   We will use SLF4J (Simple Logging Facade for Java) as an abstraction and Logback as the concrete implementation. This is a very common and powerful combination in the Java ecosystem.

6. Challenge

   Step 6: Applying Logging Best Practices

   With the logging framework in place, the final step is to use it effectively. This involves replacing all our old System.out.println calls and adopting best practices like using appropriate log levels and parameterized messages for better performance.