Is it necessary to specify the type in this case: ```var x = 10 var z: Long = x.toLong() // or can I...

# announcements

[Michael Sim]

Is it necessary to specify the type in this case:

var x = 10
var z: Long = x.toLong()
// or can I just write var z as:
var z = x.toLong()
// compiler should be able to infer the type, no?

[Shawn]

Is it necessary to specify the type in this case

no

// compiler should be able to infer the type, no?

yes

[Shawn]

are you asking because you’re seeing behavior that suggests otherwise

[Michael Sim]

I just saw this code in my book and it seemed redundant to specify the type, but as a beginner, I wasn't sure if this was best practice or how it should be written.

[Michael Sim]

Is there a way to quickly check the type in Kotlin? I had to do this in the REPL and do a if (z is Long) { println("z is Long") }

[Michael Sim]

I'm more familiar with JavaScript which has .typeof operator to check the type really quickly.

[Shawn]

there is an intention for this

[Shawn]

Screen Shot 2020-04-22 at 3.03.11 PM.png

[Shawn]

with your text cursor placed after the variable name, bring up the intentions menu (alt/option+enter on macos) and select the appropriate type hints intention to see them at a glance

[Michael Sim]

You just blew my mind. That's awesome. Thank you!

[Shawn]

also, you can get the runtime type of a variable (albeit without generics) by getting its class reference, e.g.

val foo = 42.toLong()
println(foo::class)   // class kotlin.Long

[Michael Sim]

That's really cool. This is going to speed up my learning a lot. Really appreciate it!

[Shawn]

and it might be worth mentioning that if you explicitly need a Long and are specifying a literal for it, you don’t have to call .toLong() - just append L to it: val foo = 42L. integer literals that are greater than 2³¹ - 1 are automatically allocated as Long s — see the docs: https://kotlinlang.org/docs/reference/basic-types.html

[Shawn]

happy to help 👍

[Michael Sim]

The book is good, but now I understand it better with your help 🙂 Thanks again!