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androidkotlinlazy-initialization

how to initialize a UI-component lazily

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(...) {...}
Solution

  • 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{
...
}