Regex to split a string (in Java) so that spaces are preserved?

Question

I need to split a string (in Java) into individual words ... but I need to preserve spaces.

An example of the text I need to split is something like this:
ABC . . . . DEF . . . . GHI

I need to see "ABC", " . . . .", "DEF", ". . . .", and "GHI".

Obviously splitting on the space character \s isn't going to work, as all the spaces get swallowed up as one space.

Any suggestions?

Thanks

Why do you want ". . . . " and not ". ", ". ", ". ", ". "? You only want to split on space sometimes? What are the rules exactly? — Mark Byers
Actually, that would have been fine also ... I just needed the spaces preserved. — David G

polygenelubricants polygenelubricants · Accepted Answer · 2010-06-02T19:54:28

Looks like you can just split on \b in this case ("\\b" as a string literal).

Generally you want to split on zero-width matching constructs, which \b is, but also lookarounds can be used.

Splitting based on a custom word boundary

If \b isn't fitting your definition, you can always define your own boundaries using assertions.

For example, the following regex splits on the boundary between a meta character class X and its complement

(?=[X])(?<=[^X])|(?=[^X])(?<=[X])

In the following example, we define X to be \d:

    System.out.println(java.util.Arrays.toString(
        "007james123bond".split(
            "(?=[X])(?<=[^X])|(?=[^X])(?<=[X])".replace("X", "\\d")
        )
    )); // prints "[007, james, 123, bond]"

Here's another example where X is a-z$:

    System.out.println(java.util.Arrays.toString(
        "$dollar . . blah-blah   $more gimme".split(
            "(?=[X])(?<=[^X])|(?=[^X])(?<=[X])".replace("X", "a-z$")
        )
    )); // prints "[$dollar,  . . , blah, -, blah,    , $more,  , gimme]"

Regex to split a string (in Java) so that spaces are preserved?

2 Answers

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