scala implement multiple generics types

Question

Please view this classes :

class MainClass(firstName:String) extends GenericClass[(Int,String,Long)](firstName,"David")
class GenericClass[T](str1: String, str2: String)

How scala can implement and map multiple type to single generic type ?
I mean GenericClass only have a Single type named GenericClass[T] but MainClass extends this and implement multiple type GenericClass[(Int,String,Long)]

I learn this code on slick orm :

class Suppliers(tag: Tag) extends Table[(Int, String, String, String, String, String)](tag, "SUPPLIERS") { ... }

can do like this in java language ?

(Int, String, Long) is just tuple syntax. Java has not build-in special syntax for tuples, but you can use special classes, which serve a similar purpose to tuples, like Pair<A,B> from javatuples. Nothing then stops you from doing things like GenericClass<Pair<String, String>> in Java. — Krzysztof Atłasik
– Krzysztof Atłasik, Commented May 24, 2019 at 9:25
If you want something similar to Slick in Java, look at jOOQ. And yes, because Java does not have built-in tuple types, it uses things like Record3<Integer, String, Long>. — Thilo
– Thilo, Commented May 24, 2019 at 9:41

Bogdan Vakulenko · Accepted Answer · 2019-05-24 10:13:54Z

5

GenericClass[T] has type parameter T. This parameter can be replaced by any type. In your case GenericClass[T] is parameterized by tuple (Int,String,Long) which is just a syntax sugar for Tuple3[Int,String,Long], so you can replace one with another and nothing changes:

class MainClass(firstName:String) extends GenericClass[Tuple3[Int,String,Long]](firstName,"David")

Note: Tuple3 is one type with three type parameters. Not multiple types.

As far as I know there is no equivalent of tuple class in java, but you can create it by your own or just use some librairies like javatuples

edited May 24, 2019 at 10:13

answered May 24, 2019 at 9:24

Bogdan Vakulenko

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