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Learn Scala from Scratch

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Getting to Know Scala

Scala: A History A 'Scalable' Language A Featurette: Scala Features Who's Using Scala?

Variables and Types

Variables in Scala Printing in Scala Immutable Variables Mutable Variables Data Types Challenge: Declaring a Variable Solution Review: Declaring a Variable Type Casting in Scala Challenge: Type Casting Solution Review: Type Casting Strings and Other Literals Type Inference Chapter Quiz

Operating with Operators

A Brief Introduction to Methods and Functions An Introduction to Operators Arithmetic Operators Relational Operators Logical Operators Bitwise Operators Assignment Operators Challenge: Using Multiple Operators Solution Review: Using Multiple Operators Operator Precedence Challenge: Temperature Conversion Solution Review: Temperature Conversion Chapter Quiz

Strings and How to Use Them

An Introduction String Interpolation with 's'Challenge: Embed a Variable in a String Solution Review: Embed a Variable in a String String Interpolation with 'f'Challenge: Formatting Strings Solution Review: Formatting Strings String Interpolation with 'raw'Testing String Equality Creating Multiline Strings Splitting Strings Finding Patterns in Strings Replacing Patterns in Strings Methods for Comparing Strings Challenge: Searching a String Solution Review: Searching a String Chapter Quiz

Scala's Collection Library

A Brief Introduction to Objects and Classes An Introduction to the Collection Library foreach: A Collection Method The Array Collection ArrayBuffers Challenge: Array of Integers Solution Review: Array of Integers Working with Lists Challenge: Appending an Element to a List Solution Review: Appending an Element to a List Getting Started with Vectors Creating a Range of Numbers LazyList: A Lazy Version of List Chapter Quiz

Control Structures

Control Structures in Scala Decide with if Optimizing an if Program Challenge: Pass or Fail Solution Review: Pass or Fail Loop with while Challenge: Oven is Ready!Solution Review: Oven is Ready!Iterate with for Challenge: Array of Squares Solution Review: Array of Squares Exception Handling with try Pattern Matching with Match Challenge: Color Wheel Solution Review: Color Wheel Types of Patterns Chapter Quiz

Getting Started with Functions

Defining a Function Challenge: Absolute Value Solution Review: Absolute Value Evaluation Strategies Quiz: CBV or CBN?Code Termination Recursive Functions Challenge: Sum of Lists Solution Review: Sum of Lists Learning by Example: Newton's Method Blocks Challenge: Max with Nested Functions Solution Review: Max with Nested Functions Lexical Scope Tail Recursion Challenge: Tail Recursion Solution Review: Tail Recursion Chapter Quiz

Higher-Order Functions

What are Higher-Order Functions?Learning by Example: Summation Summation with Higher-Order Functions Challenge: Write your First Higher-Order Function Solution Review: Write Your First Higher-Order Function Anonymous Functions Summation with Anonymous Functions Challenge: Anonymous Functions Solution Review: Anonymous Functions Functions Returning Functions Currying Summation with Currying Expanding a Multiple Parameter List Challenge: Using a Curried Function Solution Review: Using a Curried Function Chapter Quiz

Classes and Objects

Creating a Class in Scala

Objects of a Class

Creating an Object Using Constructor Parameters

Learning by Example: checksum

Singleton Objects: Companion

Singleton Objects: Standalone

Conclusion

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Singleton Objects: Companion

Singleton Objects: Companion

In this lesson, you will be introduced to singleton objects and learn how to write a singleton companion object.

A singleton object is defined the same way a class is defined with the difference that instead of the class keyword, we use the object keyword.

Unlike a class, which can be instantiated multiple times, a singleton object only has a single instance. This is why we cannot use new to create an instance of a singleton object.

There are two types of singleton objects:

Companion Objects
Standalone Objects

Companion Objects

A singleton object which has the ...