Need correct price regex (Java) - Mine doesnt work

Question

I'm trying to make a regex, that checks if something is a price. I'm not good at regular expressions and this one give me a regex syntax error. It should check if the input is something like 13.3 or 0.1 or .4 or 6 or 200 or 3.04, which could all be interpreted as a price. I tried using Double.valueOf(String), however, this method accepts strings like 3.00, so more than 2 floating points.

private boolean validateAndSet(JTextField tf) {
    boolean isDouble = true;
    try { 
        if (tf.getText().matches("^[0-1]*(\\.)?[0-1]{0-2}$"))   {
            item.setAlertPrice(Double.valueOf(tf.getText()));
            return true;
        }
        isDouble = false;
    } catch (NumberFormatException nfe) {
        isDouble = false;
    } finally {
        if (!isDouble) {
            System.out.println("Not a price;");
            tf.setText("0.00");
        }

    }
    return isDouble;
}

If you are using `Double` to store price, you are cheating the users of your application. — Rohit Jain, Dec 23 '12 at 18:25
It is plainly wrong to store prices as a plain floating point. In Java you should always use `BigDecimal`. — Thomas Jungblut, Dec 23 '12 at 18:26
`^[0-1]*` means your "price" can only ever be zeroes and ones (or nothing) prior to the decimal. — Brian Roach, Dec 23 '12 at 18:26
@user1924422 - read: http://stackoverflow.com/questions/3730019/why-not-use-double-or-float-to-represent-currency for why you're going to cheat people :) — Brian Roach, Dec 23 '12 at 18:38
Because you searching for prices without a specific currency, be warned: not every current is of this format. For example in Peru they have a currency of three parts: 1 Inti = 100 Centimos = 1000 Soles. ... ;-) — Ralph, Dec 23 '12 at 18:49

score 1 · Accepted Answer · answered Dec 23 '12 at 18:26

1

Wrong things about your regex:

[0-1] -> this delimites a 0 or a 1, you need to use \d to delimiter every number.
{0-2} -> this isn't correct, you need to use , instead of -

The rest I think is okay.

answered Dec 23 '12 at 18:26

Javier Diaz

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Thanks. The [0-1] was a brainfart on my side I immediately realized. – user1924422 Dec 23 '12 at 18:29

score 0 · Answer 2 · answered Dec 23 '12 at 18:26

0

Try "^[0-9]*?(\\.)?[0-9]{0,2}$", instead.

answered Dec 23 '12 at 18:26

DWright

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@Javier detected the same issue (not 0-1, but 0-9). Further, I think you need to make that * non-greedy as in my example. – DWright Dec 23 '12 at 18:28

Need correct price regex (Java) - Mine doesnt work

2 Answers2