Background

When I wrote this article, I assumed that you already know about Android programming before. If you are Android beginners, you can read my other article, “Introduction Android programming using Android Studio 3.0.”

Why Is Kotlin?

• Kotlin is very intuitive and easy to learn for Java developers
• Android Studio 3.0 can understand, compile, and run Kotlin code easily

Installing the Android Studio 3.0 and Kotlin Plugin

• We must download and install Android Studio 3.0 at  developer.android.com (current version is 3.0.1)
• Checking Kotlin plugin installed by selecting File > Settings

Creating a New Android Application Using Kotlin

• Creating a new project by selecting File > New > New Project. Enter a text for Application name and check out Include Kotlin Support checkbox as the following screenshot:

• Click Next and Next and select Empty Activity. Click Next and Finish.
• So far, we have activity_main.xml file (includes two modes: Design and Text) and MainActivity.kt file.
• In right window, select app > res > values > strings.xml. Add a string element name hello_world to strings.xml file as follows:

<resources>
    <string name="app_name">My First Kotlin App</string>
    <string name="hello_world">Hello Kotlin</string>
</resources>

• Select activity_main.xml file in Design mode. Select TextView and set a value (message) for ID and set a value (@string/hello_world) for text in Attributes window:

• Select MainActivity.kt file and adding the import as follows:

import kotlinx.android.synthetic.main.activity_main.*

• Add the following code line to the onCreate method:

message.text = "Hello My Kotlin App in Android Studio 3.0"

• Do you remember the message? It is ID of TextView.
• The complete code of MainActivity.kt, so far, can look like:

package com.example.admin.myfirstkotlinapp    
import android.support.v7.app.AppCompatActivity  
import android.os.Bundle  
import kotlinx.android.synthetic.main.activity_main.*  
class MainActivity : AppCompatActivity() {        
override fun onCreate(savedInstanceState: Bundle?) {          
     super.onCreate(savedInstanceState)          
     setContentView(R.layout.activity_main)          
     message.text = "Hello My Kotlin App in Android Studio 3.0"      
     }  }

• Run App and the message "Hello My Kotlin App in Android Studio 3.0" will display.

Conclusion

In this article, I have only introduced how to install and create a simple Android application using Kotlin in Android Studio 3.0. In my next articles, I will introduce about more Kotlin language and how to create more complicate Android applications.