Java email validation using regex

Java/email-validation-regex/email-validation-regex.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4" />

Java/email-validation-regex/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>org.javadevjournal</groupId>
+    <artifactId>email-validation-regex</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+     <dependencies>
+
+         <dependency>
+             <groupId>org.junit.jupiter</groupId>
+             <artifactId>junit-jupiter-params</artifactId>
+             <version>5.7.0</version>
+             <scope>test</scope>
+         </dependency>
+         <dependency>
+             <groupId>org.apache.logging.log4j</groupId>
+             <artifactId>log4j-api</artifactId>
+             <version>2.14.0</version>
+         </dependency>
+         <dependency>
+             <groupId>org.apache.logging.log4j</groupId>
+             <artifactId>log4j-core</artifactId>
+             <version>2.14.0</version>
+         </dependency>
+     </dependencies>
+
+</project>

Java/email-validation-regex/src/main/java/com/javadevjournal/regex/email/EmailValidation.java

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+package com.javadevjournal.regex.email;
+
+public interface EmailValidation {
+
+    boolean validateEmailAddress(final String email);
+}

Java/email-validation-regex/src/main/java/com/javadevjournal/regex/email/EmailValidationWithDomain.java

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+package com.javadevjournal.regex.email;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class EmailValidationWithDomain implements EmailValidation {
+
+    private static Pattern EMAIL_REGEX= Pattern.compile("^[A-Z0-9._%+-]+@[A-Z0-9.-]+\\.[A-Z]{2,12}$", Pattern.CASE_INSENSITIVE);
+
+    /**
+     * This email validation use the regular expression to check the email pattern.
+     * It also check the length of the domain name (e.g. .com , .net, .media etc). You can always modify
+     * the regular expression to increase the length which checking the domain name character length
+     * @param email
+     * @return
+     */
+    @Override
+    public boolean validateEmailAddress(String email) {
+        final Matcher matcher = EMAIL_REGEX.matcher(email);
+        return matcher.matches();
+    }
+}

Java/email-validation-regex/src/main/java/com/javadevjournal/regex/email/EmailValidationWithDoubleDots.java

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+package com.javadevjournal.regex.email;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class EmailValidationWithDoubleDots implements EmailValidation {
+
+    private static Pattern EMAIL_REGEX= Pattern.compile("^[a-zA-Z0-9_!#$%&'*+/=?`{|}~^-]+(?:\\\\.[a-zA-Z0-9_!#$%&'*+/=?`{|}~^-]+)*@[a-zA-Z0-9-]+(?:\\\\.[a-zA-Z0-9-]+)*$");
+
+    /**
+     * Email validation regex to restrict leading, trailing dots. It also will check if the
+     * email contains consecutive dots.
+     * @param email
+     * @return
+     */
+    @Override
+    public boolean validateEmailAddress(String email) {
+        final Matcher matcher = EMAIL_REGEX.matcher(email);
+        return matcher.matches();
+    }
+}

Java/email-validation-regex/src/main/java/com/javadevjournal/regex/email/RFC5322EmailValidation.java

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+package com.javadevjournal.regex.email;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class RFC5322EmailValidation implements EmailValidation {
+
+    private static Pattern EMAIL_REGEX= Pattern.compile("^[a-zA-Z0-9_!#$%&'*+/=?`{|}~^.-]+@[a-zA-Z0-9.-]+$", Pattern.CASE_INSENSITIVE);
+
+    /**
+     * Java regular expression to validate email using the RFC 5322. Keep in mind that it also allows
+     * few characters which can pause security risks (e.g. | character)
+     * @param email
+     * @return boolean
+     */
+    @Override
+    public boolean validateEmailAddress(String email) {
+        final Matcher matcher = EMAIL_REGEX.matcher(email);
+        return matcher.matches();
+    }
+}

Java/email-validation-regex/src/main/java/com/javadevjournal/regex/email/SimpleEmailValidation.java

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+package com.javadevjournal.regex.email;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Class contains different utility methods to validate emails
+ */
+public class SimpleEmailValidation implements EmailValidation{
+
+    private static  Pattern EMAIL_REGEX= Pattern.compile("^(.+)@(.+)$");
+
+
+    /**
+     * A simple validation which check for @ symbol and make sure there is
+     * some character before and after the @ symbol
+     * @param email
+     * @return
+     */
+    @Override
+    public boolean validateEmailAddress(String email) {
+        final Matcher matcher = EMAIL_REGEX.matcher(email);
+        return matcher.matches();
+    }
+
+}

Java/email-validation-regex/src/main/java/com/javadevjournal/regex/email/W3CHTML5EmailValidation.java

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+package com.javadevjournal.regex.email;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class W3CHTML5EmailValidation implements EmailValidation {
+
+    private static Pattern EMAIL_REGEX= Pattern.compile("^[a-zA-Z0-9.!#$%&'*+\\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$");
+
+    @Override
+    public boolean validateEmailAddress(String email) {
+        final Matcher matcher = EMAIL_REGEX.matcher(email);
+        return matcher.matches();
+    }
+}

Java/email-validation-regex/src/test/java/com/javadevjournal/regex/email/RFC5322SimpleEmailValidationTest.java

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+package com.javadevjournal.regex.email;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class RFC5322SimpleEmailValidationTest {
+
+    @ParameterizedTest(name = "#{index} - Run test with email = {0}")
+    @MethodSource("validEmailList")
+    void valid_email_test(String email){
+
+        EmailValidation validation = new RFC5322EmailValidation();
+        assertTrue(validation.validateEmailAddress(email));
+    }
+
+    @ParameterizedTest(name = "#{index} - Run test with email = {0}")
+    @MethodSource("invalidEmailList")
+    void invalid_emails_test(String email){
+        EmailValidation validation = new RFC5322EmailValidation();
+        assertFalse(validation.validateEmailAddress(email));
+    }
+
+    static List<String> validEmailList(){
+        return Arrays.asList(
+                "contact@javadevjournal.com",
+                "contact.us@javadevjournal.com",
+                "contact-us+1@javadevjournal.com",
+                "contact?us+1@javadevjournal.com"
+        );
+    }
+
+    static List<String> invalidEmailList(){
+        return Arrays.asList(
+                "@javadevjournal.com",
+                "test@dummy.com"
+        );
+    }
+}

Java/email-validation-regex/src/test/java/com/javadevjournal/regex/email/SimpleEmailValidationConsecutiveDotsTest.java

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+package com.javadevjournal.regex.email;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class SimpleEmailValidationConsecutiveDotsTest {
+
+    @ParameterizedTest
+    @MethodSource("validEmailList")
+    void valid_email_test(String email){
+
+        EmailValidation validation = new EmailValidationWithDoubleDots();
+        assertTrue(validation.validateEmailAddress(email));
+    }
+
+    @ParameterizedTest
+    @MethodSource("invalidEmailList")
+    void invalid_emails_test(String email){
+        EmailValidation validation = new EmailValidationWithDoubleDots();
+        assertFalse(validation.validateEmailAddress(email));
+    }
+
+    static List<String> validEmailList(){
+        return Arrays.asList(
+                "contact@javadevjournal.com",
+                "contact.us@javadevjournal.com",
+                "contact-us+1@javadevjournal.com"
+
+        );
+    }
+
+    static List<String> invalidEmailList(){
+        return Arrays.asList(
+                ".@javadevjournal.com",
+                "test@dummy.com.",
+                "contact@javadevjournal..com"
+        );
+    }
+}

Java/email-validation-regex/src/test/java/com/javadevjournal/regex/email/SimpleEmailValidationNonLatinTest.java

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+package com.javadevjournal.regex.email;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class SimpleEmailValidationNonLatinTest {
+
+    @ParameterizedTest
+    @MethodSource("validEmailList")
+    void validate_email(String email){
+
+        SimpleEmailValidation validation = new SimpleEmailValidation();
+       // assertTrue(validation.validateNonLatinEamil(email));
+    }
+
+    @ParameterizedTest
+    @MethodSource("invalidEmailList")
+    void invalid_emails(String email){
+
+        SimpleEmailValidation validation = new SimpleEmailValidation();
+       // assertTrue(validation.validateNonLatinEamil(email));
+    }
+
+    static List<String> validEmailList(){
+        return Arrays.asList(
+                "contact@javadevjournal.com",
+                "contact.us@javadevjournal.com",
+                "contact-us+1@javadevjournal.com",
+                "test@tüller.com"
+        );
+    }
+
+    static List<String> invalidEmailList(){
+        return Arrays.asList(
+                "contact.us#javadevjournal.com",
+                "@javadevjournal.com",
+                "test@test.corporate",
+                "test@tüller.com"
+        );
+    }
+}

Java/email-validation-regex/src/test/java/com/javadevjournal/regex/email/SimpleEmailValidationWithDomainTest.java

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+package com.javadevjournal.regex.email;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class SimpleEmailValidationWithDomainTest {
+
+    @ParameterizedTest(name = "#{index} - Test with email = {0}")
+    @MethodSource("validEmailList")
+    void validate_email_test(String email){
+
+        EmailValidation validation = new EmailValidationWithDomain();
+        assertTrue(validation.validateEmailAddress(email));
+    }
+
+    @ParameterizedTest(name = "#{index} - Test with email = {0}")
+    @MethodSource("invalidEmailList")
+    void invalid_emails_test(String email){
+
+        EmailValidation validation = new EmailValidationWithDomain();
+        assertFalse(validation.validateEmailAddress(email));
+    }
+
+    static List<String> validEmailList(){
+        return Arrays.asList(
+                "contact@javadevjournal.com",
+                "contact.us@javadevjournal.com",
+                "contact-us+1@javadevjournal.com",
+                "test@javadevjournal.media.org",
+                "test@test.corporations"
+        );
+    }
+
+    static List<String> invalidEmailList(){
+        return Arrays.asList(
+                "contact.us#javadevjournal.com",
+                "@javadevjournal.com"
+        );
+    }
+}

Java/email-validation-regex/src/test/java/com/javadevjournal/regex/email/SimpleSimpleEmailValidationTest.java

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+package com.javadevjournal.regex.email;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class SimpleSimpleEmailValidationTest {
+
+    private static final Logger LOG = LogManager.getLogger(SimpleSimpleEmailValidationTest.class);
+
+    @DisplayName("Validate email using simple regex")
+    @ParameterizedTest
+    @ValueSource(strings = {"contact-us@javadevjournal.com",
+    "contact@javadevjournal.com",
+    "contact.us@javadevjournal.com",
+    "contact-us+1@javadevjournal.com",
+     //invalid emails
+     "contact.us#javadevjournal.com",
+     "@javadevjournal.com",
+     "test@test.corporate"
+    })
+    void validate_email_simpleRegex(String email){
+
+        SimpleEmailValidation validation = new SimpleEmailValidation();
+        assertTrue(validation.validateEmailAddress(email));
+    }
+}

Java/email-validation-regex/src/test/java/com/javadevjournal/regex/email/W3CHTML5EmailValidationTest.java

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+package com.javadevjournal.regex.email;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class W3CHTML5EmailValidationTest {
+
+    @ParameterizedTest(name = "#{index} - Run test with email = {0}")
+    @MethodSource("validEmailList")
+    void valid_email_test(String email){
+
+        EmailValidation validation = new W3CHTML5EmailValidation();
+        assertTrue(validation.validateEmailAddress(email));
+    }
+
+    @ParameterizedTest(name = "#{index} - Run test with email = {0}")
+    @MethodSource("invalidEmailList")
+    void invalid_emails_test(String email){
+        EmailValidation validation = new W3CHTML5EmailValidation();
+        assertFalse(validation.validateEmailAddress(email));
+    }
+
+    static List<String> validEmailList(){
+        return Arrays.asList(
+                "contact@javadevjournal.com",
+                "contact.us@javadevjournal.com",
+                "contact-us+1@javadevjournal.com",
+                "contact?us+1@javadevjournal.com"
+        );
+    }
+
+    static List<String> invalidEmailList(){
+        return Arrays.asList(
+                "@javadevjournal.com",
+                "@javadevjournal..com",
+                "test@dummy.com",
+                "test@test.corporations",
+                 "test@126.1.1.1"
+        );
+    }
+}