how to initialize a UI-component lazily

Question

Given the below example, how can I make lazy initialization of the TextView? I attempted to do the initialization via lateinit and it worked, but it cant be done via lazy lambda function

Activity

    var mTextViewResult : TextView by lazy { findViewById(R.id.tvResult) }

    onCreate(...) {...}

Answer 1

Instead of using var you should use val

val mTextViewResult : TextView by lazy { findViewById(R.id.tvResult) }

DEPRECATED Furthermore, if kotlin android extensions plugin is applied you do not have to call findViewById() too.

In application level build.gradle add plugin for kotlin android extension

apply plugin: "com.android.application"
apply plugin: "kotlin-android"
apply plugin: "kotlin-kapt"
apply plugin: "kotlin-android-extensions" // this plugin

...

Now you can use tvResult by importing your layout reference.

import kotlinx.android.synthetic.main.<layout>.*

class MainActivity : AppCompatActivity{
...
}