Free Online Tutorials

To learn how to validate an email address, we create a simple example.

Step 1: create new android project

Step 2: create the layout: 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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.tutorialspots.emailvalidate.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TUTORIALSPOTS.COM"
        android:textColor="#FF0000"
        android:textSize="30dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:id="@+id/textView" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Enter your email address:"
        android:id="@+id/textView2"
        android:layout_below="@+id/textView"
        android:layout_centerHorizontal="true" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textEmailAddress"
        android:ems="15"
        android:id="@+id/editText"
        android:layout_below="@+id/textView2"
        android:layout_centerHorizontal="true" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Validate"
        android:id="@+id/button"
        android:onClick="validateEmail"
        android:layout_below="@+id/editText"
        android:layout_centerHorizontal="true" />
</RelativeLayout>

Step 3: file MainActivity.java

package com.tutorialspots.emailvalidate;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class MainActivity extends AppCompatActivity {
    EditText editText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        editText = (EditText) findViewById(R.id.editText);
    }

    public void validateEmail(View view){
        String email = editText.getText().toString();
        if(isValidEmail(email)){
            Toast.makeText(view.getContext(), "Email is valid", Toast.LENGTH_LONG).show();
        }else{
            Toast.makeText(view.getContext(), "Email is invalid", Toast.LENGTH_LONG).show();
        }
    }

    public static boolean isValidEmail(String email)
    {
        String expression = "^[\\w\\.]+@([\\w]+\\.)+[A-Z]{2,7}$";
        CharSequence inputString = email;
        Pattern pattern = Pattern.compile(expression, Pattern.CASE_INSENSITIVE);
        Matcher matcher = pattern.matcher(inputString);
        if (matcher.matches())
        {
            return true;
        }
        else{
            return false;
        }
    }
}

Step 4: run for test