I need help finding a regex that will allow most strings, except:

• if the string only contains whitespaces
• if the string contains : or *

I want to reject the following strings:

• "hello:world"
• "hello*world"
• " " (just a whitespace)

But the following strings will pass:

• "hello world"
• "hello"

So far, I can accomplish what I want... in two patterns.

• [^:*]* rejects the 2 special characters
• .*\S.* rejects any string with only whitespaces

I'm not sure how to combine these two patterns into one...

I'll be using the regex pattern along with Java.

CodePudding user response：

An example of how you could combine your two patterns for use with the matches method:

"[^:*]*[^:*\\s][^:*]*"

[^\s] is equivalent to \S.

CodePudding user response：

You could use a negative lookahead:

^(?!\s*$)[^:*] $

• ^ - start of string anchor
• (?!\s*$) negative lookahead rejecting whitespace-only strings
• [^:*] - one or more of any character except : and *
• $ - end of string anchor

Demo