Regex not working in method replaceAll() - Android

Question

I asked a question here: Regex: Differentiate boundary match ^ and Negation about a regex to be applied in method replaceAll(), to get a String with only digits and the minus sign (-) to allow negative numbers as well. I run the follow and it works fine in my java interpreter:

String onlyDigits = currencyStringValue.replaceAll("[\\D-]","").replaceAll("(?<!^)-","");

If I input: --25#54d51 -> Returns: -255451

25#54-d51 -> Returns: 255151

-25#54d51 -> Returns: -255451

dz-255451 -> Returns: -255451

But I'm trying the same thing in Android Studio, and only returns digits, debugging the app, I notice the onlyDigits get only numbers 0-9, ignoring the minus sign (-) in beginning...

What is it wrong and if there is a problem in code or solution, how can I solve this?

Thanks!

replaceAll("[\\D]","") removes any non-digit character including -. What are you trying to do here? — Pshemo
– Pshemo, Commented Mar 22, 2016 at 23:19
Try String onlyDigits = currencyStringValue.replaceAll("[^-\\d]","").replaceAll("(?<!^)-","");. — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Mar 22, 2016 at 23:20
@Pshemo I changed to replaceAll("[\\D-]","").replaceAll("(?<!^)-","") and the problem kept. But I corrected my code with the suggestion from the answer below and now It works fine — tdmsoares
– tdmsoares, Commented Mar 22, 2016 at 23:33
Isn't that same solution which you already get here: stackoverflow.com/a/36144843/1393766? — Pshemo
– Pshemo, Commented Mar 22, 2016 at 23:34

Wiktor Stribiżew · Accepted Answer · 2016-03-22 23:27:39Z

1

The problem is with \D that matches any character but a digit. With the first replacement operation you remove all minuses together with other non-digits.

The solution is simple: turn \D into a negated character class [^\d] and add a hyphen into it so as to avoid removing minuses before the next replaceAll call.

Use

String onlyDigits = currencyStringValue.replaceAll("[^-\\d]","").replaceAll("(?<!^)-","");

See the IDEONE demo

answered Mar 22, 2016 at 23:27

Wiktor Stribiżew

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1 Comment

tdmsoares Over a year ago

Thanks a lot! Before it was my mistake, but I corrected and the problem happened again. But now thanks to you it works fine!

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