Alphanumeric validation

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1

Does anyone know a PURE JSP way of doing Alphanumeric validation on a text input?

2

Use regegular expressions, for example:


String str = "somestring";
if(str.matches("[a-zA-Z0-9]")) {
  // do something here if it matches.
} else {
  // doesn't match do something else.
}
3

I can’t get it to return true, am I missing something?

Edit: I forgot that I had to search from the start to the end of the string. :blush:

4

How do you search from the start to the end of the string? Adding a asterisk after the regexp?

Like that:

if(str.matches(“[a-zA-Z0-9]*”))

What if I want only number? Can I do something like:

if(!str.matches(“[0-9]”))

Thanks

5

Sorry for the late reply but I have been busy.

To match the start of a string, start the pattern with a ^ character. If you want to match at the end, conclude the pattern with a $ character.

I use this link as a reference when I’m about to create regexp’s: http://www.evolt.org/article/Regular_Expressions_in_JavaScript/17/36435/index.html
Even though it’s a Javascript article, I find it useful. I’m sure you will find Java-related articles with examples if you search a little. :slight_smile:

6

What snaily posted will only match a single character. Add * to it to match multiple, but unless you want to match an empty string, use + instead
[a-zA-Z0-9]+