{"id":16860,"date":"2018-05-30T06:05:41","date_gmt":"2018-05-30T06:05:41","guid":{"rendered":"https:\/\/data-flair.training\/blogs\/?p=16860"},"modified":"2021-12-04T10:15:40","modified_gmt":"2021-12-04T04:45:40","slug":"scala-final","status":"publish","type":"post","link":"https:\/\/data-flair.training\/blogs\/scala-final\/","title":{"rendered":"Scala Final – Variable, Method & Class | Scala This"},"content":{"rendered":"

In this Scala Programming tutorial<\/strong><\/a>, we will talk about two keywords called Scala This and Scala Final. Along with this, we will also discuss an example of Scala Final & Scala This. In Scala Final, we will discuss Scala Final Variables, Methods, and Class with their examples.<\/p>\n

So, let’s start Scala Final Tutorial.<\/p>\n

\"Scala<\/a>

Scala Final – Variable, Method & Class | Scala This<\/p><\/div>\n

What is Scala This & Scala Final?<\/h3>\n

In Scala, the \u2018this\u2019 keyword lets us refer to the current object. \u2018final\u2019 prevents a class from deriving members from its superclass. These can be variables, methods, and classes. Let\u2019s first learn about \u2018this\u2019.<\/p>\n

Let’s discuss Scala Variables with Examples<\/a><\/strong><\/p>\n

a. Scala This<\/h4>\n

When we want to refer to the current object for a class, we use the \u2018this\u2019 keyword. Then using the dot operator, we can refer to instance variables, and the class\u2019 methods and constructors.<\/p>\n

Let\u2019s take an example.<\/p>\n

Example. 1 Scala This-\u00a0<\/strong><\/p>\n

Let\u2019s see how \u2018 Scala This\u2019 works. In the following example, we use \u2018Scala This\u2019 to call the primary constructor and the instance variables.<\/p>\n

scala> class Marks{\r\n| var midterm=0\r\n| var finals=0\r\n| def this(midterm:Int,finals:Int){\r\n| this()\r\n| this.midterm=midterm\r\n| this.finals=finals | }\r\n| def show(){\r\n| println(\"You've got \"+midterm+\" in midterms and \"+finals+\" in finals\u201d)\r\n| }\r\n| }\u00a0\r\ndefined class Marks\r\nscala> var chemistry=new Marks(96,99)\u00a0\r\nchemistry: Marks = Marks@7e3ee128\r\nscala> chemistry.show()<\/pre>\n
You’ve got 96 in midterms and 99 in finals.<\/p>\n
Must read about Scala Case Class | Create Scala Object<\/a><\/strong><\/p>\n
Example. 2 Scala This-\u00a0<\/strong><\/p>\n
scala> class Calculator(a:Int){\r\n| def this(a:Int,b:Int){\r\n| this(a)\r\n| println(a+\"+\"+b+\"=\"+{+b})\r\n| }\r\n| }\u00a0\r\ndefined class Calculator\r\nscala> var c=new Calculator(3,4)\r\n3+4=7\r\nc: Calculator = Calculator@3723de42<\/pre>\n
Here, we call one constructor from another. This call statement has to be the first statement in this body.<\/p>\n
Example. 3 Scala This-\u00a0<\/strong><\/p>\n
scala> class Calculator(){\r\n| def this(a:Int){\r\n| this()\r\n| println(a)\r\n| }\r\n| }\u00a0\r\ndefined class Calculator\r\nscala> var c=new Calculator(3)\r\n3\r\nc: Calculator = Calculator@4e8036bb\r\nscala> var d=new Calculator()\r\nd: Calculator = Calculator@45c3cf0c<\/pre>\n
Let’s explore Scala String Method with Syntax and Method<\/a><\/strong><\/p>\n
b. Scala Final<\/h4>\n
When we don\u2019t want a class to be able to inherit a member from its superclass, we declare that member final. This member may be a variable, a method, or even a class.<\/p>\n
i. Scala Final Variables<\/h5>\n
When a variable is \u2018final\u2019, we cannot override it in the subclass.<\/p>\n
scala> class Super{\r\n| final var age=18\r\n| }\u00a0\r\ndefined class Super\r\nscala> class Sub extends Super{\r\n| override var age=21\r\n| def show(){\r\n| println(\"age=\"+age)\r\n| }\r\n| }\r\n<console>:13: error: overriding variable age in class Super of type Int;\r\nvariable age cannot override final member\r\noverride var age=21\r\n^<\/pre>\n
As you can see, Scala threw an error when we tried to override the final variable.<\/p>\n
Let’s Discuss Scala Access Modifiers: Public, Private and Protected Members<\/a><\/strong><\/p>\n
ii. Scala Final Methods<\/h5>\n
Like the Scala final variable, a final method won\u2019t let you override it in the subclass. Let\u2019s watch.<\/p>\n
scala> class Super{\r\n| final def show(){\r\n| println(\"Hello\")\r\n| }\r\n| }\u00a0\r\ndefined class Super\r\nscala> class Sub extends Super{\r\n| override def show(){\r\n| println(\"Hi\")\r\n| }\r\n| }\r\n<console>:13: error: overriding method show in class Super of type ()Unit;\r\nmethod show cannot override final member\r\noverride def show(){\r\n^<\/pre>\n
Learn Scala Closures with Examples\u00a0<\/a><\/strong><\/p>\n
iii. Scala Final Classes<\/h5>\n
Finally, when we don\u2019t want a class to be inheritable, we declare it \u2018final\u2019. This means another class cannot extend it.<\/p>\n
scala> final class Super{\r\n| def show(){\r\n| println(\"Hello\")\r\n| }\r\n| }\r\ndefined class Super\r\nscala> class Sub extends Super{\r\n| def sayhi(){\r\n| println(\"Hi\")\r\n| }\r\n| }\r\n<console>:12: error: illegal inheritance from final class Super\r\nclass Sub extends Super{\r\n^<\/pre>\n
Let’s explore Scala Functions: Quick and Easy Tutorial<\/a><\/strong><\/p>\n
So, this was all about Scala Final tutorial. Hope you like our Explanation on Scala This.<\/p>\n
Conclusion<\/h3>\n
Hence, in this tutorial, we studied “Scala This” lets us refer to the current object and “Scala Final” stops us from overriding a variable or a method and inheriting a class. In addition, we talked about Scala Final Variables, Methods & Classes with their examples. Drop your queries in the comments.<\/p>\n
Related Topic-\u00a0\u00a0Scala Exceptions and Exception Handling<\/a><\/strong><\/p>\n
For reference<\/a><\/strong>
In this Scala Programming tutorial, we will talk about two keywords called Scala This and Scala Final. Along with this, we will also discuss an example of Scala Final & Scala This. In Scala...<\/p>\n","protected":false},"author":6,"featured_media":16863,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[61],"tags":[4346,12452,12454,12455,12558],"class_list":["post-16860","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-scala","tag-example-of-scala-this","tag-scala-final-examlpe","tag-scala-final-methods","tag-scala-final-variable","tag-scala-this-example"],"yoast_head":"\nScala Final - Variable, Method & Class | Scala This - DataFlair<\/title>\n<meta name=\"description\" content=\"What is Scala This, What is Scala Final, Scala Final Variables, Scala FInal Methods, Scala Final Classes, Examples of Scala This, Scala FInal example\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/data-flair.training\/blogs\/scala-final\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Scala Final - 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