Unresolved Reference: findViewById in Kotlin

Question

fun Tryouts() {
var CheckBox1 : CheckBox = findViewById(R.id.ForwardBox) as CheckBox
CheckBox1.setChecked(false)
}

I'm still a beginner in Kotlin having learnt only the basic working of kotlin, I am unable refer to any android widget or change it's state in Android Studio whether it's TextView or CheckBox or RadioBox.
Same Unresolved Reference errors for findViewById in all cases...
I don't know what is it that I am doing wrong, even java conversion outputs the same errors.

Answer 1

It seems this is the easiest way to get rid of findViewById ()

Go to your Build.Gradle (Module: app)

Add the following line

apply plugin: 'kotlin-android-extensions'

• Then it will ask you to sync
• Then press sync

After that come to your Activity file Say it many be MainActivity.kt

There import To import single view

import kotlinx.android.synthetic.main.<layout_name>.<view_name>;

or

To import all views

import kotlinx.android.synthetic.main.<layout_name>.*;

Example : in your Layout

<Checkbox id="@+/forwardBox" . .  . />

it is in activity_main layout then import as

import kotlinx.android.synthetic.main.activity_main.forwardBox;

so either in your function or class use it directly

forwardBox.isChecked = false

Answer 2

In Kotlin you do not need to use findViewById, Simply use id ForwardBox from kotlinx.android.synthetic.<your layout name>. All used elements in your code gets automatically found and assigned to same variable name as ids in layout(xml) by kotlin.

For example:

fun init(){
    ForwardBox.isChecked = false
}