Replace everything except positive/negative numbers

Question

There are many questions already answered for replacing everything positive numbers. But, I couldn't find any answer which preserves both positive and negative numbers. I want to replace everything that isn't number(positive or negative). The output should be the following eg.

0 | success. id - 1234| -> 0 1234

and

-10 | failure. id - 2345| -> -10 2345

Apparently this answers for the positive part.

Whited

Answer 1

You can use this regex to match positive/negative integers:

[+-]?\b\d+\b

RegEx Demo

to match positive/negative numbers including decimals:

[+-]?\b\d+(?:\.\d+)?\b

Please note that rather than using replace you would be better off using above regex in Pattern and Matcher APIs and just get your matched data.

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In case you can only use replace then use:

str = str.replaceAll( "([+-]?\\b\\d+\\b)|\\S+[ \\t]*", "$1" );

Replace Demo

Magi

what is the use of equals sign? – Whited

0 | success. id - 1234| is returning 01234 and not 0 1234 in your replaceall regex – Whited

Hmm this demo shows a space between 0 and 1234 but replace is not recommended, better to use matching. – Magi

Answer 2

I used this in Kotlin to replace all non-Double characters before parsing to a Double:

val double = str.replace("[^0-9.-]".toRegex(), "").toDoubleOrNull()

Dysarthria