Book Image

Learning Scala Programming

By : Vikash Sharma
Book Image

Learning Scala Programming

By: Vikash Sharma

Overview of this book

Scala is a general-purpose programming language that supports both functional and object-oriented programming paradigms. Due to its concise design and versatility, Scala's applications have been extended to a wide variety of fields such as data science and cluster computing. You will learn to write highly scalable, concurrent, and testable programs to meet everyday software requirements. We will begin by understanding the language basics, syntax, core data types, literals, variables, and more. From here you will be introduced to data structures with Scala and you will learn to work with higher-order functions. Scala's powerful collections framework will help you get the best out of immutable data structures and utilize them effectively. You will then be introduced to concepts such as pattern matching, case classes, and functional programming features. From here, you will learn to work with Scala's object-oriented features. Going forward, you will learn about asynchronous and reactive programming with Scala, where you will be introduced to the Akka framework. Finally, you will learn the interoperability of Scala and Java. After reading this book, you'll be well versed with this language and its features, and you will be able to write scalable, concurrent, and reactive programs in Scala.
Table of Contents (21 chapters)
Title Page
Packt Upsell
Contributors
Preface
Index

Exception handling – the old way


Let's write some code so that we can talk about exception handling. Take a look at the following:

def toInt(str: String): Int = str.toInt 

In the preceding code, the toInt is a function that takes a String value, which supposedly can be converted to a corresponding Int value. The definition looks okay, but as functional programmers, we are so used to trying out the function to see whether it does what it says (in the definition). Let's try out some calls to this function:

println(toInt("121")) 
println(toInt("-199")) 

The preceding code gives the following result:

121 
-199 

Things worked fine for us. We passed a number in a string format and got the corresponding integer values. But what if you try something like the following:

println(toInt("+ -199")) 

Say that we get something unexpected, some exception saying this:

Exception in thread "main" java.lang.NumberFormatException: For input string: "+ -199" 
   at java.lang.NumberFormatException.forInputString(NumberFormatException...