Regex to find the @ sign within a string

Question

I need help with my regex so it can find if there is an @ sign within the string I'm searching.

import java.util.regex.*;
public class OnlineNewspaperSubscription extends NewspaperSubscription
{
    public void setAddress(String a)
    {

         address = a;

        // Creating a pattern from regex
        Pattern pattern
            = Pattern.compile("@*");

        // Get the String to be matched
        String stringToBeMatch = a;

        // Create a matcher for the input String
        Matcher matcher = pattern.matcher(stringToBeMatch);

       if(matcher.matches())
        {
            super.rate = 9;

        }
       else
        {
            super.rate = 0;
            System.out.println("Need an @ sign");
        }

    }

}

I should be able to tell whether this string is an email address or not.

Why use a regex? You can use `String#contains()` or `String#indexOf()` — Phil, Apr 04 '19 at 00:45
Change regex from `"@*"` to `"@"` and change `matches()` to `find()`. — Andreas, Apr 04 '19 at 00:46
I thought regex would be easier to get this in but I'll try the indexOf — , Apr 04 '19 at 00:47
Partly duplicate of [Difference between matches() and find() in Java Regex](https://stackoverflow.com/q/4450045/5221149) — Andreas, Apr 04 '19 at 00:53
`I should be able to tell whether this string is an email address or not` with the @, yeah sure thing. — , Apr 04 '19 at 01:06
"I should be able to tell whether this string is an email address or not." is Select client.name, "@" from Clients an email address? — Scuba Steve, Apr 04 '19 at 03:08

score 2 · Answer 1 · answered Apr 04 '19 at 00:47

2

You don't need a regular expression to find the index of '@' in a String; use String.indexOf(int) (passing a char). Like,

int p = a.indexOf('@');
if (p > -1) {
    // ...
}

answered Apr 04 '19 at 00:47

Elliott Frisch

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Allan · Answer 2 · 2019-04-04T01:45:01.860

You do not need to use regex for this, it is an overkill. You can just use the method contains() from the String class available from java 1.5 (if I remember correctly). This method does actually use internally indexOf().

System.out.println("Does not contain :" + "Does not contain".contains("@"));
System.out.println("Does cont@in :" + "Does not cont@in".contains("@"));

output:

Does not contain @:false
Does contain @:true

Notes:

If what you want to do is validate the format of an email address, checking the presence of an @ is not sufficient, I would recommend using a regex for this.

Example: https://stackoverflow.com/a/8204716/8794221

Regex to find the @ sign within a string

2 Answers2