Testing a string for numeric characters

Question

Possible Duplicate:
Java: how to check that a string is parsable to a double?

What is the best way to check a string for numeric characters in Java?

    try {
        NumberFormat defForm = NumberFormat.getInstance();            
        Number n = defForm.parse(s);      
        double d = n.doubleValue();
    } 
    catch (Exception ex) {
        // Do something here...    
    }

Or is there a better way using REGEX?

I don't want to strip the numbers.

Also, which kinds of numbers would you want to allow? I'm thinking `1e4` - is that a valid number for you? How about `NaN` or `-Inf`? — Tim Pietzcker, Jun 25 '12 at 11:07
The string could be "56" or "aaa56aaa". Can anyone suggest a regex? — Mr Morgan, Jun 25 '12 at 11:08
A regex to do what exactly? Find any embedded number? Find out *if* there is any embedded number? — Tim Pietzcker, Jun 25 '12 at 11:10
Also, to the close-voters: This is not a duplicate of said question. — Tim Pietzcker, Jun 25 '12 at 11:12

score 2 · Answer 1 · edited Jul 14 '12 at 21:50

2

String test = "12cats";
//String test = "catscats";
//String test = "c4ts";
//String test = "12345";
if (test.matches(".*[0-9].*") {
    System.out.println("Contains numbers");
} else {
    System.out.println("Does not contain numbers");
} //End if

edited Jul 14 '12 at 21:50

Jason Sturges

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answered Jun 25 '12 at 11:14

swapy

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score 1 · Accepted Answer · answered Jun 25 '12 at 11:11

1

using regex u can do it this way -

String s="aa56aa";
Pattern pattern = Pattern.compile("\\d");
Matcher matcher = pattern.matcher(s);

System.out.println(matcher.find());

answered Jun 25 '12 at 11:11

Kshitij

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score 0 · Answer 3 · answered Jun 25 '12 at 11:08

0

A good solution would be to use a regex (link <- here you have everything you need to work wih regexes).

answered Jun 25 '12 at 11:08

overbet13

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This is not an answer to the OP's question (vague as it is). – Tim Pietzcker Jun 25 '12 at 11:11
Thanks for pointing that out. But sincerely, the question is of a "lmgtfy" category – overbet13 Jun 25 '12 at 11:19
In case you don't know: "lmgtfy" stands for "Let Me Google That For You" :) – overbet13 Jun 25 '12 at 11:38
I do know this, and you might like to know that answers of this kind are considered rude on StackOverflow and are likely to get downvoted and/or deleted. – Tim Pietzcker Jun 25 '12 at 12:07
Thanks again for pointing that out, sir. – overbet13 Jun 25 '12 at 13:19

user278064 · Answer 4 · 2012-06-25T11:14:18.077

0

/**
 * Return true if your string contains a number,
 * false otherwise.
 */
str.matches("\\d+");

e.g.:

"csvw10vsdvsv".matches("\\d+"); // true
"aaa".matches("\\d+"); // false

edited Jun 25 '12 at 11:14

answered Jun 25 '12 at 11:08

user278064

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Get an illegal character \92 char message here. Any ideas? – Mr Morgan Jun 25 '12 at 11:14
@MrMorgan: Sorry. I mixed javascript with Java. I changed my solution. Take a look! – user278064 Jun 25 '12 at 11:15

Testing a string for numeric characters

4 Answers4