Regular expression is not working as expected in apex

Question

I'm working on design patterns while I'm testing in the anonymous window it's working as expected. But when i trying to implement the same logic it's unable to find matches

My expression:'^([0-9])\\1*$|(?i)NA|\\[not provided\\]|^([_])\\1*$|[^\\w]*|(?i)[a-z]{5,}|(?i)[A-Z]{5,}|\\d{5,}|(?i)N/A|(?i)test|(?i)testing';

So, I'm trying to implement every single logic individually. My requirement is to find any field contains only special characters.

First Logic: [^\\w]*

I'm unable to understand why my logic is not working on an apex class. But working on the apex class. By the way, I'm using matches method

String emailId='Azuga Cavalry0';
Boolean result = false;
    Pattern EmailPattern = Pattern.compile(emailRegex);
    Matcher EmailMatcher = EmailPattern.matcher(emailId.trim());
    if(EmailMatcher.matches())
    {
        result=true;
        System.debug('Result details'+result);
    }

With the guidance of @sfdcfox i have found out the issues within my regular expression and updated the expression. One of my requirement is to find the fields which have only special characters.

My logic: \\p{Punct}+ And I'm using matches method only because I'm looking for a total field instead of specific words.

Answer 1

matches() matches the entire string against the pattern. What you're looking for is find(), which finds the first matching occurrence. Next, remember that * matches zero or more occurrences. You want at least one occurrence, which would be +. So, it should look like this:

String emailRegex = '[^\\w]+';
String emailId='Azuga Cavalry0';
Boolean result = false;
Pattern EmailPattern = Pattern.compile(emailRegex);
Matcher EmailMatcher = EmailPattern.matcher(emailId.trim());
if(EmailMatcher.find()) {
    result = true;
    System.debug('Result details'+result);
}

Rather than try to make a monster regex, which is difficult, consider a list of things you want to look for:

String[] patterns = new String[] {
  '^([0-9])\\1*$', '(?i)NA', ...
};
Boolean found = false;
for(String patt: patterns) {
  Pattern p = Pattern.compile(patt);
  Matcher m = p.matcher(emailString);
  found = m.find();
  if(found) {
    break;
  }
}

This will run slightly slower, but is often much easier than trying to build an entire string to match against.

It's also probably worth mentioning that simply validating for a valid email is probably easier than validating a select set of invalid emails, because you never know when someone might surprise you with something you didn't think of, resulting in a game of cat and mouse trying to keep out all the invalid values.