How to rotate an image in imageview by an angle on Android using Kotlin?

This example demonstrates how to rotate an image in imageview by an angle on 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"
   android:padding="2dp"
   tools:context=".MainActivity">
   <ImageView
      android:id="@+id/imageView"
      android:layout_width="match_parent"
      android:layout_height="600dp"
      android:src="@drawable/image" />
   <Button
      android:layout_above="@+id/imageView"
      android:id="@+id/btnRotate"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignParentBottom="true"
      android:layout_centerInParent="true"
      android:text="Rotate View"
      android:textStyle="bold" />
</RelativeLayout>

Step 3 − Add the following code to src/MainActivity.kt

import android.os.Bundle
import android.widget.Button
import android.widget.ImageView
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
   lateinit var imageView: ImageView
   lateinit var btnRotate: Button
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
      imageView = findViewById(R.id.imageView)
      btnRotate = findViewById(R.id.btnRotate)
      btnRotate.setOnClickListener { imageView.rotation = 90f }
   }
}

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