"Not enough information to infer parameter T" with Kotlin and Android

You must be using API level 26 (or above). This version has changed the signature of View.findViewById() - see here https://developer.android.com/about/versions/oreo/android-8.0-changes#fvbi-signature

So in your case, where the result of findViewById is ambiguous, you need to supply the type:

1/ Change

val listView = findViewById(R.id.list) as ListView to

val listView = findViewById<ListView>(R.id.list)

2/ Change

this.label = row?.findViewById(R.id.label) as TextView to

this.label = row?.findViewById<TextView>(R.id.label) as TextView

Note that in 2/ the cast is only required because row is nullable. If label was nullable too, or if you made row not nullable, it wouldn't be required.

Andoid O change findViewById api from

public View findViewById(int id);

to

public final T findViewById(int id)

so, if you are target to API 26, you can change

val listView = findViewById(R.id.list) as ListView

to

val listView = findViewById(R.id.list)

or

val listView: ListView = findViewById(R.id.list)

Its Working

API Level 25 or below use this

    var et_user_name = findViewById(R.id.et_user_name) as EditText

API Level 26 or Above use this

    val et_user_name: EditText = findViewById(R.id.et_user_name)

Happy Coding !