Regular expression to remove specific characters in email addresses

Question

Im trying to figure out how i can remove certain characters in an email address before the domain name using nothing but a simple regex and replaceAll in Java.

In email addresses,

Need to remove any number of . before @<domain name>
Also remove anything between + up to @ but not including @. For instance in [email protected] should be [email protected].

So far I have,

class Main {
  public static void main(String[] args) {
    String matchingRegex = "(\\.|(\\+.*(?=@)))";
    System.out.println("[email protected]".replaceAll(matchingRegex, ""));
  }
}

which replaces everything including the domain name. joebloggs@gmailcom

What i really need is [email protected]. Can this be achieved with regex alone ?

That's because the beginning of your regex accounts for *all* periods: `\\.|otherStuff` is saying "Periods OR other stuff". Since periods *after* the @ fit the regex (due to that first statement of `\\.` followed by a `|`), they're also being removed. — Vince, Dec 05 '19 at 03:35
Oh, my bad, didn't see it in the test string at first. Still, your regex says "Periods OR a + followed by *any character* behind a @". That first expression, the `\\.` followed by a pipe, is what's causing all your periods to be replaced. — Vince, Dec 05 '19 at 03:42
@VinceEmigh Yup definitely. Is there anyway for that first part to say search up to `@` ? — nixgadget, Dec 05 '19 at 03:45

score 2 · Accepted Answer · answered Dec 05 '19 at 04:15

Another look ahead did the trick in the end.

class Main {
  public static void main(String[] args) {
    String matchingRegex = "((\\.+)(?=.*@)|(\\+.*(?=@)))";
    System.out.println("[email protected]".replaceAll(matchingRegex, ""));
    System.out.println("[email protected]".replaceAll(matchingRegex, ""));
    System.out.println("[email protected]".replaceAll(matchingRegex, ""));
    System.out.println("[email protected]".replaceAll(matchingRegex, ""));
    System.out.println("[email protected]".replaceAll(matchingRegex, ""));
    System.out.println("[email protected]".replaceAll(matchingRegex, ""));
    System.out.println("[email protected]".replaceAll(matchingRegex, ""));
  }
}

Results in,

[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]

score 1 · Answer 2 · answered Dec 05 '19 at 03:34

1

You could try spliting the string (the email) on the @ and running replaceAll on the the first half and then put the strings back together.

Check out: How to split a string in Java

For splitting strings.

answered Dec 05 '19 at 03:34

notansandwich

59
1
7

Or he could fix his regex. Although this is answer may work, it creates overhead which could easily be avoided if using the proper regular expression. – Vince Dec 05 '19 at 03:36
Splitting would be easy but like i said it should be a regex and `replaceAll`. – nixgadget Dec 05 '19 at 03:38

score 1 · Answer 3 · answered Dec 05 '19 at 14:40

1

Try this regex [.](?=.*@)|(?=\\+)(.*)(?=@). It looks up dots up to @ (even if there's text in between), or everything from + up to @. Hope it helps https://regex101.com/r/gyUpta/1

class Main {
 public static void main(String[] args) {

    String matchingRegex = "[.](?=.*@)|(?=\\+)(.*)(?=@)";
    System.out.println("[email protected]".replaceAll(matchingRegex, ""));
 }
}

answered Dec 05 '19 at 14:40

Gabriel Macus

444
1
4
9

Nice. thats also another way to do it. – nixgadget Dec 06 '19 at 10:42

score 0 · Answer 4 · answered Dec 05 '19 at 03:37

This will do the trick...

public static void main(String args[]) {
       String matchingRegex = "(\\.|(\\+.*(?=@)))";
       String email = "[email protected]";
       String user = email.substring(0, email.indexOf("@")+1);
       String domain = email.substring(email.indexOf("@")+1);          
       System.out.println(user.replaceAll(matchingRegex, "") + domain);
   }

score 0 · Answer 5 · answered Dec 05 '19 at 04:06

This is the easiest way I have found to do it.

      String address = "[email protected]";
      int at = address.indexOf("@");

      address = address.substring(0, at).replaceAll("\\.|\\+.*", "")
            + address.substring(at);

      System.out.println(address);

score 0 · Answer 6 · answered Dec 05 '19 at 04:15

if you try to split for regex sorry i don't remember java this example is in javascript

let string = "[email protected]"

//firts the function
function splitString(params) {
    return params.split(/\+(.)+\@/)
}

//second the concat
let list = splitString(string)
//     the first element+the las element 
console.log(`${list[0]}${list[list.length -1]}`)

Regular expression to remove specific characters in email addresses

6 Answers6