Regex for checking if a string is strictly alphanumeric

Question

How can I check if a string contains only numbers and alphabets ie. is alphanumeric?

Answer 1

Use character classes:

^[[:alnum:]]*$

Answer 2

Pattern pattern = Pattern.compile("^[a-zA-Z0-9]*$");
Matcher matcher = pattern.matcher("Teststring123");
if(matcher.matches()) {
     // yay! alphanumeric!
}

Answer 3

100% alphanumeric RegEx (it contains only alphanumeric, not even integers & characters, only alphanumeric)

For example:

special char (not allowed)
123 (not allowed)
asdf (not allowed)
1235asdf (allowed)

---

String name="^[^<a-zA-Z>]\\d*[a-zA-Z][a-zA-Z\\d]*$";

Answer 4

In order to be unicode compatible:

^[\pL\pN]+$

where

\pL stands for any letter
\pN stands for any number