Scala basics [introduction and installation]

One Scala introduction

1 What is? Scala

In English ,Scala Not a word , It is Scalable Language An abbreviation for two words , Express the meaning of scalable language . From a computer point of view ,Scala Is a complete software programming language , Then linking together means Scala Is a scalable software programming language . So it's scalable , Because this language embodies object-oriented , Functional programming and other different language paradigms , And it integrates the new features of different languages .

Scala The programming language was developed by the Federal Institute of technology in Lausanne （EPFL） Of Martin Odersky On 2001 Year based on Funnel The work began to design and develop . because Martin Odersky My previous work was to develop general purpose Java and Javac（Sun The company's Java compiler ）, So based on the Java Platform Scala Language in 2003 end of the year /2004 Released early this year .

Scala Official website ：https://www.scala-lang.org/

At present, the main batch computing engine framework of big data Spark Is based on Scala Language development , The main streaming computing engine framework Flink Also provided Scala Corresponding API, And the development efficiency of functional programming in the big data field is higher , More intuitive , Easier to understand .

Martin Odersky Is an avid compiler enthusiast , After a long time of programming , Hope to develop a language , It can make the process of writing programs simple , Efficient , So when it comes to Java After language , Feel the charm of this language , Decided to integrate the features of functional programming language into Java In language , And out of that came 2 Gate language （Pizza & Scala）, These two languages have greatly promoted Java The development of language

• JDK1.5 The generic , enhance for loop , Automatic type conversion and so on are from Pizza New features introduced by the language
• JDK1.8 Type inference of ,λ（lambda） The expression is derived from Scala New features introduced by the language

It can be seen from the above that ,Scala Language is based on Java Developed , Therefore, the compiled file is also a bytecode file , And can run on JVM in .

2 scala install

（1） Environmental installation

 install JDK1.8
 Unzip the file ：scala-2.12.11.zip, The unzipped directory should be free of Chinese and spaces 
 Configure environment variables 

stay windows Run under cmd, Enter the following command , The following message appears, indicating that the installation is successful .

（2）Scala Plug in installation

By default IDEA I won't support it Scala Development of , Need to install Scala plug-in unit .
File-Settings- Search for Scala- Click the right button （install）

If the download is slow , Please visit the website ：https://plugins.jetbrains.com/plugin/1347-scala/versions

（3）hello scala

① establish maven project

② increase Scala Framework support

By default ,IDEA When creating a project in... Is not supported Scala Development of , Need to add Scala Framework support .

Right click the project name , choice scala, take scala Install directory configuration

③ Create a class

package com.hike.bigdata.scala.chapter01

object Scala01_HelloWorld {
    
  def main(args: Array[String]): Unit = {
    
    System.out.println("Hello Scala World")
  }
}