Kotlin Kotlin Android Extensions Using Views
Example
Assuming we have an activity with an example layout called activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="@+id/my_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="My button"/>
</LinearLayout>
We can use Kotlin extensions to call the button without any additional binding like so:
import kotlinx.android.synthetic.main.activity_main.my_button
class MainActivity: Activity() {
override fun onCreate(savedInstanceBundle: Bundle?) {
super.onCreate(savedInstanceBundle)
setContentView(R.layout.activity_main)
// my_button is already casted to a proper type of "Button"
// instead of being a "View"
my_button.setText("Kotlin rocks!")
}
}
You can also import all ids appearing in layout with a * notation
// my_button can be used the same way as before
import kotlinx.android.synthetic.main.activity_main.*
Synthetic views can't be used outside of Activities/Fragments/Views with that layout inflated:
import kotlinx.android.synthetic.main.activity_main.my_button
class NotAView {
init {
// This sample won't compile!
my_button.setText("Kotlin rocks!")
}
}
