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javaregexstringdigit

Using regex to check if a string contains only one digit

I'm writing an algorithm and I need to check if a string contains only one digit (no more than one). Currently I have:

if(current_Operation.matches("\\d")){
...
}

Is there a better way to go about doing this? Thanks.

Solution

  • You can use:

    ^\\D*\\d\\D*$
# match beginning of the line
# non digits - \D*
# one digit - \d
# non digits - \D*
# end of the line $

    See a demo on regex101.com (added newlines for clarity).