Add Check Email

Strings/CheckEmail.java

@@ -0,0 +1,34 @@
+package Strings;
+
+import java.util.Objects;
+import java.util.regex.Pattern;
+
+/**
+ * Example of email address validation. Checks if a given string is a valid email or not.
+ */
+public class CheckEmail {
+
+  public static void main(String[] args) {
+    assert isEmail("hello@gmail.com");
+    assert isEmail("iamweasel@yahoo.com.mx");
+    assert isEmail("coco@hotmail.com");
+    assert !isEmail("coco@hotmail@google.com");
+    assert !isEmail("www.google.com");
+    assert !isEmail("hello world");
+    assert !isEmail(null);
+  }
+
+  /**
+   * Checks if the given string is an email address
+   *
+   * @param stringToEvaluate the string to evaluate
+   * @return {@code true} if stringToEvaluate is an email address, otherwise {@code false}
+   */
+  public static boolean isEmail(String stringToEvaluate) {
+    if(Objects.isNull(stringToEvaluate)) return false;
+    String emailRegex = "^[A-Za-z0-9_+&*-]+(?:\\.[A-Za-z0-9_+&*-]+)*@(?:[A-Za-z0-9-]+\\.)+[A-Za-z]{2,7}$";
+    return Pattern.compile(emailRegex)
+            .matcher(stringToEvaluate)
+            .matches();
+  }
+}