Where and how to use static variables in Android using Kotlin?

This example demonstrates how to use static variables in Android using Kotlin.
Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.
Step 2 − Add the following code to res/layout/activity_main.xml.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".MainActivity">
   <TextView
      android:id="@+id/text2"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="70dp"
      android:background="#008080"
      android:padding="5dp"
      android:text="TutorialsPoint"
      android:textColor="#fff"
      android:textSize="24sp"
      android:textStyle="bold" />
   <TextView
      android:id="@+id/Question"
      android:layout_width="wrap_content"
      android:layout_height="93dp"
      android:layout_centerInParent="true"
      android:padding="8dp"
      android:text="I'm a Static Variable"
      android:textColor="@android:color/background_dark"
      android:textSize="32sp"
      android:textStyle="bold"
      tools:layout_editor_absoluteY="8dp" />
</RelativeLayout>
Step 3 − Add the following code to src/MainActivity.kt
import android.os.Bundle
import android.util.Log
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
   private val tag = "I'm a Static Variable"
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
   }
   override fun onStart() {
      super.onStart()
      Log.i(tag, "onStart")
      Toast.makeText(baseContext, "onStart", Toast.LENGTH_SHORT).show()
   }
   override fun onPause() {
      super.onPause()
      Log.i(tag, "onPause")
      Toast.makeText(baseContext, "onPause", Toast.LENGTH_SHORT).show()
   }
   override fun onStop() {
      super.onStop()
      Log.i(tag, "onStop")
      Toast.makeText(baseContext, "onStop", Toast.LENGTH_SHORT).show()
   }
}
Step 4 − Add the following code to androidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.example.q11">
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>
Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click the Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen.