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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. 



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