Why Does My Java Regex Email Validation Fail Despite Working in Eclipse's Find and Replace?

Trouble with Java Regex Email Validation

In attempting to validate email addresses using a regular expression, a Java user has encountered a problem where the validation fails even for well-formed email addresses. Despite the fact that the regex matches email addresses when used in a "find and replace" function within Eclipse, it fails when used with Java's Pattern and Matcher classes.

The regex in question is:

\b[A-Z0-9._%-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b

The user has employed this code in Java:

Pattern p = Pattern.compile("\b[A-Z0-9._%-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b");
Matcher m = p.matcher("[email protected]");

if (m.find())
    System.out.println("Correct!");

However, regardless of the email address being valid or invalid, the regex validation fails.

A Potential Solution

A suggested solution is to utilize the following Java code, which employs a similar regex:

public static final Pattern VALID_EMAIL_ADDRESS_REGEX = Pattern.compile("^}[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,6}$", Pattern.CASE_INSENSITIVE);

public static boolean validate(String emailStr) {
    Matcher matcher = VALID_EMAIL_ADDRESS_REGEX.matcher(emailStr);
    return matcher.matches();
}

This code has been reported to validate email addresses reliably.

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