How should I validate an e-mail address in Android?

This example demonstrates how do I validate an email address in android.

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="8dp"
   tools:context=".MainActivity">
   <EditText
      android:layout_centerInParent="true"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:hint="Enter Email Address"
      android:id="@+id/editText"/>
   <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignParentEnd="true"
      android:layout_below="@id/editText"
      android:layout_marginTop="5dp"
      android:text="Validate"
      android:onClick="Validate"/>
</RelativeLayout>

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

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
   EditText editText;
   String email;
   String emailPattern = "[a-zA-Z0-9._-]+@[a-z]+\.+[a-z]+";
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      editText = findViewById(R.id.editText);
      email = editText.getText().toString().trim();
   }
   public void Validate(View view) {
      if (email.matches(emailPattern)) {
         Toast.makeText(getApplicationContext(), "Valid email address", Toast.LENGTH_SHORT).show();
      } else {
         Toast.makeText(getApplicationContext(), "Invalid email address", 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="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.