{"id":925,"date":"2022-08-17T20:21:47","date_gmt":"2022-08-17T20:21:47","guid":{"rendered":"https:\/\/datmt.com\/?p=925"},"modified":"2022-08-17T20:21:48","modified_gmt":"2022-08-17T20:21:48","slug":"scala-variables-tutorial","status":"publish","type":"post","link":"https:\/\/datmt.com\/scala\/scala-variables-tutorial\/","title":{"rendered":"Scala Variables Tutorial"},"content":{"rendered":"\n

Declaring variables in Scala is quite simple. The language offers some very nice mechanisms to let developers declare variables with ease.<\/p>\n\n\n\n

Mutable variables<\/h2>\n\n\n\n

To declare mutable variables (variables that you can assign to a different value after declaring), you need to use the keyword var<\/code>:<\/p>\n\n\n\n

  def mutableVariable(): Unit =\n    var x = 100;\n    println(s"x is: ${x}")\n    x = 200\n    println(s"x is: ${x}"<\/pre><\/div>\n\n\n\n
Immutable variables<\/h2>\n\n\n\n
To declare immutable variables, instead of using var<\/code>, you need to use val<\/code><\/p>\n\n\n\n
  def immutableVariable(): Unit =\n    val x = 100\n<\/pre><\/div>\n\n\n\n
Trying to assign x to another value would cause a compiler error:<\/p>\n\n\n\n
\n  def immutableVariable(): Unit =\n    val x = 100\n    x = 100 \/\/<- this would cause a compiler error<\/pre><\/div>\n\n\n\n
\"Build
Build failed due to immutable variable reassignment<\/figcaption><\/figure>\n\n\n\n
Type inference<\/h2>\n\n\n\n
As you can see from the examples above, I declared variables without specifying the types. This is not because Scala is a loosely typed language like Javascript. Instead, it infers the type based on the value you assign to the variables.<\/p>\n\n\n\n
You can specify the type of the variables if you want to. <\/p>\n\n\n\n
  def typeInference(): Unit =\n\n   val dog1 = GSD_Dog("Joe")\n    println("type of dog1: " + dog1.getClass)\n\n    val x : String = "hello"\n    println("type of x: " + x.getClass)\n\n    var m = 100f\n    println("type of m: " + m.getClass)\n\n    var n = 100\n    println("type of n: " + n.getClass)\n<\/pre><\/div>\n\n\n\n
Calling this function produces the following results:<\/p>\n\n\n\n
\"Type
Type inference in Scala<\/figcaption><\/figure>\n\n\n\n
Multiple variables declaration<\/h2>\n\n\n\n
You can declare multiple variables (mutable and immutable on one line) like this:<\/p>\n\n\n\n
  def multipleVariableDeclaration(): Unit =\n    var (x: Int, y: String, z: Boolean) = (100, "Hello", false)\n    println(s"x = $x, y = $y, z = $z")\n<\/pre><\/div>\n\n\n\n
Calling the function would produce the correct values for x, y, z respectively:<\/p>\n\n\n\n
\"Multiple
Multiple variables declaration<\/figcaption><\/figure>\n\n\n\n
Variable scopes<\/h2>\n\n\n\n
There are three variable scopes in Scala:<\/p>\n\n\n\n
  • Field (class variable)<\/li>
  • Method parameters (arguments passed to methods)<\/li>
  • Local (variables declared inside methods)<\/li><\/ul>\n\n\n\n
    Here is the example of the scopes:<\/p>\n\n\n\n
    case class GSD_Dog(name: String) {\n  val breed: String = "GSD"\n  \n  def reportState(isSleeping: Boolean = true): Unit =\n    var report = "Not sleeping"\n    if (isSleeping) then\n      report = "I'm busy"\n      \n    println(report)\n}<\/pre><\/div>\n\n\n\n
    In this example,<\/p>\n\n\n\n
    •  breed<\/code> has field scope.<\/li>
    • isSleeping<\/code> has method parameters scope<\/li>
    • report<\/code> has local variable scopes<\/li><\/ul>\n\n\n\n
      Conclusion<\/h2>\n\n\n\n
      In this post, I’ve introduced you to Scala variables. To recap, variables in Scala can be mutable or immutable. When declaring variables, you can specify their types or leave for type inference to do the work.<\/p>\n","protected":false},"excerpt":{"rendered":"
      Declaring variables in Scala is quite simple. The language offers some very nice mechanisms to let developers declare variables with ease.<\/p>\n","protected":false},"author":1,"featured_media":929,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"footnotes":""},"categories":[124],"tags":[127,131,132],"class_list":["post-925","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-scala","tag-scala","tag-scala-tutorial","tag-scala-variables"],"yoast_head":"\nScala Variables Tutorial - datmt<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/datmt.com\/scala\/scala-variables-tutorial\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Scala Variables Tutorial - datmt\" \/>\n<meta property=\"og:description\" content=\"Declaring variables in Scala is quite simple. 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