Does Java regard a 'normal' space as whitespace for the purposes of Character.isWhitespace?

Question

This might seem to be a no-brainer at first glance. It probably is, but a few things have me feeling I might be missing something. First the Java documentation for Character.isWhitespace seems to exclude it. The definition for what is and what is not allowed as whitespace seems very definitive ('if and only if') and the first line says not a non-breaking space.

I have always regarded an ordinary 'space' - that thing you get when you press a spacebar - as a non-breaking space.

So where does it fit in the list? The list is regarded as definitive in the highest rated answer to this question - am I simply reading it wrong? Also, the first commenter to the top answer in this question seems to have his doubts (in a different context). Yet when I construct a simple bit of code to test, it indicates that a normal space is an instance of whitespace, as one would expect.

import static java.lang.Character.isWhitespace;

public class WhitespaceCheck {

   public static void main(String[] args) {

        Character test = ' ';

        if (Character.isWhitespace(test)) {
            System.out.println("Is whitespace!" );                        
        } else {
            System.out.println("Is not whitespace!" );
        }
    }
}

So, am I reading the first item on the list wrongly, is it somewhere else on the list, or is the list itself simply wrong?

I think the documentation _does_ state that it is included, because `SPACE_SEPARATOR` is `U+0020` if I'm not mistaken — , Nov 19 '15 at 22:15
I have used non-breaking spaces in Microsoft Word to prevent a line break from occurring between words that I really wanted to be kept together. They were entered using Ctrl+Shift+Spacebar. They should not be confused with the character that is usually produced by pressing the spacebar alone. — , Nov 19 '15 at 22:18
@a_horse_with_no_name Nearly there! As the other answer says, `U+0020` is included in the category of Unicode covered by SPACE_SEPARATOR. — Ger, Nov 19 '15 at 23:05

score 12 · Accepted Answer · edited Nov 20 '15 at 14:00

You are mistaken; a non-breaking space prevents a line break. It's a special type of space and not a "normal" one which does allow a line break. If a "normal" space was a non-breaking space then lines would never wrap when you reached the edge of the screen unless you pressed return manually each time.

The very first line says:

It is a Unicode space character (SPACE_SEPARATOR, LINE_SEPARATOR, or PARAGRAPH_SEPARATOR) but is not also a non-breaking space ('\u00A0', '\u2007', '\u202F')

A list of unicode whitespace covered by SPACE_SEPARATOR can be found here:

https://en.wikipedia.org/wiki/Whitespace_character

The documentation for SPACE_SEPARATOR says that it is referring to a category of Unicode characters, not a specific character. The 'normal' space of the title (which is what is usually produced by the spacebar) is included in this category.

Does Java regard a 'normal' space as whitespace for the purposes of Character.isWhitespace?

1 Answers1