Create a button and handle on click listener in Android Studio (Kotlin)

How to create a button and handle OnClickListener in Kotlin using Android Studio?

      DESCRIPTION      

In this tutorial we will create a button and handle button click. We will display a Toast on the click of that button. However you can do your own functionality such as moving to some activity, opening fragment etc.

      VIDEO      

      SOURCE CODE      

Step 1: Create a new Project or open new project

Step 2: Code

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Click Button"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

MainActivity.kt

package com.blogspot.atifsoftwares.myapplication

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.Toast

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val mBtn = findViewById<Button>(R.id.btn) as Button
        mBtn.setOnClickListener {
            Toast.makeText(this, "Button is clicked", Toast.LENGTH_LONG).show();
        }

    }
}

Step 3: Run Project

Output