Scala - Scalable Language

Scala, short for Scalable Language-

•             Created by Martin Odersky

•             Is object-oriented & functional Programming language

•             Scala runs on the JVM

Installations

•             Install Java

•             Set Your Java Environment. Ex- JAVA_HOME, PATH, etc

•             Install Scala

•             After installation, verify version by typing on command prompt or shell

>scala –version

>java –version

If you have a good understanding on Java, then it will be very easy for you to learn Scala. But, we would again describe basics as below –

1. Object - Have states and behaviors. Ex- A dog is black Color (State) and it is honest (behavior) than Humans
2. Class – Behaviors & states can be defined in a template. This template is your class. For example – Class “Living Being” defines state Legs and various Objects can have different states 0, 1, 2, 3 or 4 Legs.
3. Methods – It is basically a behavior. It is in methods where the logics are written, data is manipulated and all the actions are executed.
4. Fields – Object variables are called fields. An object's state is created by the values assigned to these fields.
5. Closure - A closure is a function, whose return value depends on the value of one or more variables declared outside this function.
6. Traits - A trait encapsulates method and field definitions. Traits are used to define object types by specifying the signature of the supported methods.

How to run –

• Either use or external Editor. For example Eclipse, etc.
• Or, Use Interactive Method-

1. Open the command prompt
2. Execute command "scala"

Welcome to Scala version 2.11.7 (Java HotSpot(TM) Client VM, Java 1.7.0_25).

Type in expressions to have them evaluated.

Type :help for more information.

scala> println("Hello, Scala")

Hello, Scala

• Or Script Mode
• Open Notepad write below code & save as HelloWorld.scala

object HelloWorld {    /* This is my first java program.     * This will print 'Hello World' as the output    */    def main(args: Array[String]) {       println("Hello, world!") // prints Hello World    } }

• Open the command prompt 
• Use ‘scalac’ command to compile the Scala program 

> scalac HelloWorld.scala

• Use ‘scala’ command to run bytecode on JVM

> scala HelloWorld Hello, World!

Scala has some coding conventions that should be followed while Programming –

• Case Sensitivity - Identifier Dinesh & dinesh is different.
• Class Names – First Letter of name in upper Case. And if multiple words then follow camel case.
• Method Names - Start with a Lower Case letter. And if multiple words then follow camel case.
• Program File Name – Name of Object class and File should be same with an extension “.scala”
• Program execution starts from the main() method which is a mandatory part of every Scala Program.