How to Rotate image in image view by an angle in Android?

This example demonstrates how to Rotate image in image view by an angle.
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"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:id="@+id/parent"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".MainActivity"
   android:gravity="center"
   android:orientation="vertical">
   <ImageView
      android:id="@+id/imageView"
      android:src="@mipmap/ic_launcher"
      android:layout_width=" wrap_content"
      android:layout_height=" wrap_content" />
   <TextView
      android:id="@+id/textChanger"
      android:layout_margin="20dp"
      android:textAlignment="center"
      android:text="Initial text"
      android:layout_width="match_parent"
      android:layout_height="wrap_content" />
</LinearLayout>
In the above code, we have taken Image view and text view. When a user clicks on Text view, Image will rotate to the 20-degree angle.
Step 3 − Add the following code to src/MainActivity.java
package com.example.andy.myapplication;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.support.annotation.RequiresApi;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
   int view = R.layout.activity_main;
   TextView textChanger;
   ImageView imageView;
   @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(view);
      textChanger = findViewById(R.id.textChanger);
      imageView=findViewById(R.id.imageView);
      textChanger.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            roateImage(imageView);
         }
      });
   }
   private void roateImage(ImageView imageView) {
      Matrix matrix = new Matrix();
      imageView.setScaleType(ImageView.ScaleType.MATRIX); //required
      matrix.postRotate((float) 20, imageView.getDrawable().getBounds().width()/2,    imageView.getDrawable().getBounds().height()/2);
      imageView.setImageMatrix(matrix);
   }
}
In the above code, we have to used roateImage() and passed imageview as shown below -
Matrix matrix = new Matrix();
imageView.setScaleType(ImageView.ScaleType.MATRIX); //required
matrix.postRotate((float) 20, imageView.getDrawable().getBounds().width()/2, imageView.getDrawable().getBounds().height()/2);
imageView.setImageMatrix(matrix);
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 the android studio, open one of your project's activity files and click Run  icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen −
In the above code, it is a default screen. When user click on "initial text" text view, it will rotate 20 degrees as shown below -
Click here to download the project code