Book Image

Learn Java with Projects

By : Dr. Seán Kennedy, Maaike van Putten
5 (3)
Book Image

Learn Java with Projects

5 (3)
By: Dr. Seán Kennedy, Maaike van Putten

Overview of this book

Learn Java with Projects stands out in the world of Java guides; while some books skim the surface and others get lost in too much detail, this one finds a nice middle ground. You’ll begin by exploring the fundamentals of Java, from its primitive data types through to loops and arrays. Next, you’ll move on to object-oriented programming (OOP), where you’ll get to grips with key topics such as classes, objects, encapsulation, inheritance, polymorphism, interfaces, and more. The chapters are designed in a way that focuses on topics that really matter in real-life work situations. No extra fluff here, so that you get more time to spend on the basics and form a solid foundation. As you make progress, you’ll learn advanced topics including generics, collections, lambda expressions, streams and concurrency. This book doesn't just talk about theory—it shows you how things work with little projects, which eventually add up to one big project that brings it all together. By the end of this Java book, you’ll have sound practical knowledge of Java and a helpful guide to walk you through the important parts of Java.
Table of Contents (22 chapters)
1
Part 1: Java Fundamentals
9
Part 2: Object-Oriented Programming
15
Part 3: Advanced Topics

The catch or declare principle

The catch or declare principle states that when a method can throw a checked exception, the method must catch the exception with a try-catch statement or declare that it throws the exception in its method signature. This rule ensures that checked exceptions are properly handled or propagated up the call stack so that the calling method can handle them.

Understanding the principle

The catch or declare principle holds for checked exceptions. If a checked exception is not declared or caught, the code won’t compile. For unchecked exceptions, the catch or declare rule does not apply. They are usually caused by programming errors or unexpected situations that cannot be predicted or anticipated. Unchecked exceptions can be caught and handled, but it is not mandatory. Let’s see how we can declare exceptions.

Now that we have seen how to declare exceptions, let’s have a look at how to deal with exceptions with the try-catch statement...