Kotlin Programming Cookbook

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We can use Anko, a library by Kotlin to reduce the code even further. Anko provides an onClick() method that accepts a lambda that gets executed onClick event:

class HelloWorldActivity2 : AppCompatActivity() {    override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        setContentView(R.layout.activity_main)        setSupportActionBar(toolbar)        supportActionBar?.title = "Let's click"        btn1.onClick { toast("Button 1 has been clicked by you! One") }        btn2.onClick { toast("Button 2 has been clicked by you! Two") }        btn3.onClick { toast("Button 3 has been clicked by you! Three") }    }}