Explanation

Question

im currently doing a little project for school. I have to check if a string is of the following type:

"One or more whitespaces" - "On ore more whitespaces"

For example: String s = " - "

I could trim the string and check only for "-", but that doesnt work because "-" should be handled differently than " - "

I currently tried something like this:

if (f.equals(" {1,} -  {1,}"))..

but i have no idead what that is exactly doing and it doenst work either.

Can someone help me out?

Shari

Answer 1

Try this regex: "^\\s+-\\s$+"

You can use String.matches(), because .equals doesn't do regexes.

"Untainted" version: ^\s+-\s+$

^ and $ anchor to the ends of the string.

\s+ matches one or more whitespace(s).

Answer 2

You need to use groups. Use ( and ) to establish groups. To answer your question I think this would work:

^(\s+) - (\s+)$
(\s+|\s*) - (\s+|\s*)

the * means 0 or more the + means 1 or more, so if you're matching 1 or more, you should have no white spaces around your pattern ie: -

A very good 'toy' is this. Just hovering over the characters shows you details, you have a cheat-sheet and many more!

Answer 3

reg = "\s+-\s+"

这可能会这样做。