Java regex splitting, but only removing one whitespace

Question

I have this code:

String[] parts = sentence.split("\\s");

and a sentence like: "this is a whitespace and I want to split it" (note there are 3 whitespaces after "whitespace")

I want to split it in a way, where only the last whitespace will be removed, keeping the original message intact. The output should be

"[this], [is], [a], [whitespace ], [and], [I], [want], [to], [split], [it]" (two whitespaces after the word "whitespace")

Can I do this with regex and if not, is there even a way?

I removed the + from \\s+ to only remove one whitespace

What should happen in situation when after last word there are also spaces like "foo bar " (there are two spaces after each word). What should be result here? — Pshemo
– Pshemo, Commented Nov 30, 2022 at 15:33

Wiktor Stribiżew · Accepted Answer · 2022-11-30 15:28:42Z

2

You can use

String[] parts = sentence.split("\\s(?=\\S)");

That will split with a whitespace char that is immediately followed with a non-whitespace char.

See the regex demo. Details:

\s - a whitespace char
(?=\S) - a positive lookahead that requires a non-whitespace char to appear immediately to the right of the current location.

To make it fully Unicode-aware in Java, add the (?U) (Pattern.UNICODE_CHARACTER_CLASS option equivalent) embedded flag option: .split("(?U)\\s(?=\\S)").

answered Nov 30, 2022 at 15:28

Wiktor Stribiżew

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1 Comment

stneric Over a year ago

Thank you so much! You're a real life saver! :)

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