how do i obtain an instance of a class without specifying it kotlinlang #getting-started

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Title

s

Smallville7123

04/09/2019, 1:58 AM

how do i obtain an instance of a class without specifying it explicitly

fun ret() {
    class a {
        var empty: Int = 0
    }

    val f = arrayListOf<a>()
    f.add(a()) // class a is explicitly specified
}

s

serebit

04/09/2019, 2:03 AM

You can't. And that's all I'm going to say. You need to read the docs

s

Smallville7123

04/09/2019, 2:05 AM

if i do v.add(v::class.java as E) then i get a type of

class java.lang.Class

why ;-; isnt the JVM meant to be able to know what type of class X is?

i

ilya.gorbunov

04/09/2019, 2:39 AM

Read about the type erasure in JVM generics. In run time

ArrayList<a>

doesn't know its element type, so you cannot obtain it with reflection.

Why do you need to instantiate class

without specifying its name?

Perhaps if you need to add something to a list and you don't have anything to add, just declare the list having nullable elements and add

null

there.

2 Views

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