CODEWITHSUNDEEP
javaregex
Prashant
Prashant

Reputation: 429

Why java fails regex expression

I wrote a condition with regex str.matches("\\D+") read with Scanner but on entering char+digit this test fails for example 3x or e3 but it should not happen. It should pass any non digit occurrence anywhere in the string even if its a symbol.

Upvotes: 0

Views: 74

Answers (4)

anubhava
anubhava

Reputation: 784968

This call fails to match 3e since:

str.matches("\\D+")

is same as:

str.matches("^\\D+$")

Because String#matches takes given regex and matches the complete input.

To make sure there is at least one non-digit, you should better use this lookahead based regex:

str.matches("(?=\\d*\\D).*")

Where (?=\\d*\\D) is positive lookahead that makes sure there is at least 1 non-digit in the given input.

Upvotes: 0

ajb
ajb

Reputation: 31689

If m is a Matcher, then m.matches returns true only if the entire string matches the pattern. If you want to just check whether some part of the string matches, you can use m.find instead of m.matches. (Note: I'm not sure whether that's actually the problem you're having.)

Upvotes: 3

MxLDevs
MxLDevs

Reputation: 19506

atleast once a non digit occurrence should be there thats what i'm saying, should pass

How about this

.*\D.*

You can test it here.

Upvotes: 1

Luuk
Luuk

Reputation: 76

\D matches any non-numeric character, so of course it will fail if you pass it a string with digits in it.

If you want to match only characters and numbers you could do something like:

matches("[a-zA-Z0-9"]+);

Upvotes: -1

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