How to determine Android device screen size category (small, normal, large, xlarge) programatically?

This example demonstrates how do I determine the Android device screen size category (small, normal, large, xlarge) programmatically.
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="16dp"
   tools:context=".MainActivity">
   <Button
      android:id="@+id/btnGetScreenSize"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:onClick="GetScreenSize"
      android:text="Get ScreenSize" />
   <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_below="@id/btnGetScreenSize"
      android:layout_centerInParent="true"
      android:layout_marginTop="10dp"
      android:onClick="GetScreenDensity"
      android:text="Get Screen Density" />
   <TextView
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_marginTop="40dp"
      android:text="Android device screen size category (small, normal, large, xlarge)"
      android:textAlignment="center"
      android:textSize="24sp"
      android:textStyle="bold|italic" />
</RelativeLayout>
Step 3 − Add the following code to src/MainActivity.java
import androidx.appcompat.app.AppCompatActivity;
import android.content.res.Configuration;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.view.View;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
   }
   public void GetScreenSize(View view) {
      if ((getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) == Configuration.SCREENLAYOUT_SIZE_LARGE) {
         Toast.makeText(this, "Large screen", Toast.LENGTH_LONG).show();
      }
      else if ((getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) == Configuration.SCREENLAYOUT_SIZE_NORMAL) {
         Toast.makeText(this, "Normal sized screen", Toast.LENGTH_LONG).show();
      }
      else if ((getResources().getConfiguration().screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) == Configuration.SCREENLAYOUT_SIZE_SMALL) {
         Toast.makeText(this, "Small sized screen", Toast.LENGTH_LONG).show();
      } else {
         Toast.makeText(this, "Screen size is neither large, normal or small", Toast.LENGTH_LONG).show();
      }
   }
   public void GetScreenDensity(View view) {
      DisplayMetrics metrics = new DisplayMetrics();
      getWindowManager().getDefaultDisplay().getMetrics(metrics);
      int density = metrics.densityDpi;
      if (density == DisplayMetrics.DENSITY_HIGH) {
         Toast.makeText(this, "DENSITY_HIGH... Density is " + (density), Toast.LENGTH_LONG).show();
      }
      else if (density == DisplayMetrics.DENSITY_MEDIUM) {
         Toast.makeText(this, "DENSITY_MEDIUM... Density is " + (density), Toast.LENGTH_LONG).show();
      }
      else if (density == DisplayMetrics.DENSITY_LOW) {
         Toast.makeText(this, "DENSITY_LOW... Density is " + (density), Toast.LENGTH_LONG).show();
      }
      else {
         Toast.makeText(this, "Density is neither HIGH, MEDIUM OR LOW. Density is " + (density), Toast.LENGTH_LONG).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="app.com.sample">
   <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 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 −
Click here to download the project code.