I have this piece of Java code:

MaterialDialog builder = new MaterialDialog.Builder(MainActivity.this)

I want to get the MainActivity object in Kotlin. The automatic conversion breaks at MainActivity.this.


Ответов: 8

Ответы (8)

You can get a reference to your MainActivity object in Kotlin by using a qualified this. e.g.:

class MyActivity : MainActivity() {
    val builder = MaterialDialog.Builder(this@MyActivity)

You can get the object of activity like this.

class DemoActivity : BaseActivity() {
    val builder = MaterialDialog.Builder(this@DemoActivity)

getActivity() equivalent is this@activity_name in case of builder for materialDialog

materialDialog = MaterialDialog.Builder(this)

In kotlin


is equivalent to JAVA


Just as you do in java for getting the context of activity as MainActivtiy.this , in kotlin you will get the context as this@MainActivity

If you are calling Activity.this from an inner class, you have to put inner before the class

class MyActivity : MainActivity() {
    // Call from class itself
    val builder = MaterialDialog.Builder(this@MyActivity) 

    inner class Inner {
        this@MyActivity // Call from the inner class 

Try this label instead


Answer is: this@ActivityName

For example: You should use it if you would like to define "Context" in MainActivity.kt

var mContext:Context = this@MainActivity

Why? Because in Kotlin language @ has mean "of" such as:

val a = this@A // A's this

If you want to learn more information, you can look Kotlin Language website: This Expression in Kotlin

2022 WebDevInsider