Book Image

Java Fundamentals

By : Gazihan Alankus, Rogério Theodoro de Brito, Basheer Ahamed Fazal, Vinicius Isola, Miles Obare
Book Image

Java Fundamentals

By: Gazihan Alankus, Rogério Theodoro de Brito, Basheer Ahamed Fazal, Vinicius Isola, Miles Obare

Overview of this book

Since its inception, Java has stormed the programming world. Its features and functionalities provide developers with the tools needed to write robust cross-platform applications. Java Fundamentals introduces you to these tools and functionalities that will enable you to create Java programs. The book begins with an introduction to the language, its philosophy, and evolution over time, until the latest release. You'll learn how the javac/java tools work and what Java packages are - the way a Java program is usually organized. Once you are comfortable with this, you'll be introduced to advanced concepts of the language, such as control flow keywords. You'll explore object-oriented programming and the part it plays in making Java what it is. In the concluding chapters, you'll get to grips with classes, typecasting, and interfaces, and understand the use of data structures, arrays, strings, handling exceptions, and creating generics. By the end of this book, you will have learned to write programs, automate tasks, and follow advanced courses on algorithms and data structures or explore more advanced Java courses.
Table of Contents (12 chapters)
Java Fundamentals
Preface

Exception Mechanics


In the previous topics, we threw and caught exceptions and got a feel for how exceptions work. Now let's revisit the mechanics to make sure we got everything right.

How try/catch Works

The try/catch statement has two blocks: the try block and the catch block, as shown here:

try {
   // the try block
} catch (Exception e) {
   // the catch block, can be multiple 
}

The try block is where your main execution path code goes. You optimistically write your program here. If an exception happens in any of the lines in the try block, the execution stops at that line and jumps to the catch block:

try {
   // line1, fine
   // line2, fine
   // line3, EXCEPTION!
   // line4, skipped
   // line5, skipped
} catch (Exception e) {
   // comes here after line3
}

The catch block catches throwables if they can be assigned to the exception reference it contains (Exception e, in this case). So, if you have an exception class here that is high up in the exception hierarchy (such as Exception...