Whitespaces in java

Question

What are kinds of whitespaces in Java? I need to check in my code if the text contains any whitespaces.

My code is:

if (text.contains(" ") || text.contains("\t") || text.contains("\r") 
       || text.contains("\n"))   
{  
   //code goes here
}

I already know about \n ,\t ,\r and space.

http://stackoverflow.com/questions/4731055/whitespace-matching-regex-java — perilbrain, Aug 08 '12 at 11:32
I had to change one line of code to `if (Character.isWhitespace(text.charAt(i)) || Character.isSpaceChar(text.charAt(i))) {` to get the results I wanted. — ericharlow, Nov 25 '13 at 23:19

Mark Byers · Answer 1 · 2012-08-08T13:40:15.233

For a non-regular expression approach, you can check Character.isWhitespace for each character.

boolean containsWhitespace(String s) {
    for (int i = 0; i < s.length(); ++i) {
        if (Character.isWhitespace(s.charAt(i)) {
            return true;
        }
    }
    return false;
}

Which are the white spaces in Java?

The documentation specifies what Java considers to be whitespace:

public static boolean isWhitespace(char ch)

Determines if the specified character is white space according to Java. A character is a Java whitespace character if and only if it satisfies one of the following criteria:

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

It is '\u0009', HORIZONTAL TABULATION.

It is '\u000A', LINE FEED.

It is '\u000B', VERTICAL TABULATION.

It is '\u000C', FORM FEED.

It is '\u000D', CARRIAGE RETURN.

It is '\u001C', FILE SEPARATOR.

It is '\u001D', GROUP SEPARATOR.

It is '\u001E', RECORD SEPARATOR.

It is '\u001F', UNIT SEPARATOR.

score 12 · Accepted Answer · edited Oct 07 '14 at 15:15

12

boolean containsWhitespace = false;
for (int i = 0; i < text.length() && !containsWhitespace; i++) {
    if (Character.isWhitespace(text.charAt(i)) {
        containsWhitespace = true;
    }
}
return containsWhitespace;

or, using Guava,

boolean containsWhitespace = CharMatcher.WHITESPACE.matchesAnyOf(text);

edited Oct 07 '14 at 15:15

Kiril Tonev

68
4

answered Aug 08 '12 at 11:30

JB Nizet

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4

or put that in a method to return the boolean and avoid the awkward `break` and "accumulator" variable. – Thilo Aug 08 '12 at 11:31
Would there be any reason here to use [Character#isWhitespace(int)](http://docs.oracle.com/javase/7/docs/api/java/lang/Character.html#isWhitespace(int)) instead of the suggested [Character#isWhitespace(char)](http://docs.oracle.com/javase/7/docs/api/java/lang/Character.html#isWhitespace(char))? – Martin Andersson Apr 03 '13 at 18:32
1

@MartinAndersson (2 years late) the [Character#isWhitespace(int)](http://docs.oracle.com/javase/7/docs/api/java/lang/Character.html#isWhitespace(int)) version accepts a [codepoint](https://en.wikipedia.org/wiki/Code_point) which you would get using [Character#codePointAt(...)](http://docs.oracle.com/javase/7/docs/api/java/lang/Character.html#codePointAt(char[],%20int)). The codepoint could span multiple chars in the string. For example the documentation mentions that is detects LINE_SEPARATOR and PARAGRAPH_SEPARATOR '\u2007', '\u202F' which are more than 8 bits wide – Sparky Dec 08 '15 at 19:32
The `!containsWhiteSpace` test should come first, not last, and in any case the variable is redundant, as the `true` case can be replaced by `return true` and the fall-through case by `return false`. – user207421 Dec 01 '16 at 10:29
Or you can leave the loop with break; after containsWhitespace was set to true. This would lead to a simpler condition in the for loop. – Lord_PedantenStein Mar 24 '18 at 19:24

score 3 · Answer 3 · answered Aug 08 '12 at 11:40

3

If you want to consider a regular expression based way of doing it

if(text.split("\\s").length > 1){
    //text contains whitespace
}

answered Aug 08 '12 at 11:40

James

2,483
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score 2 · Answer 4 · edited May 23 '17 at 12:18

2

Use Character.isWhitespace() rather than creating your own.

In Java how does one turn a String into a char or a char into a String?

edited May 23 '17 at 12:18

Community

1
1

answered Aug 08 '12 at 11:30

Aravind Yarram

78,777
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score 2 · Answer 5 · answered Aug 01 '16 at 10:17

If you can use apache.commons.lang in your project, the easiest way would be just to use the method provided there:

public static boolean containsWhitespace(CharSequence seq)

Check whether the given CharSequence contains any whitespace characters.

Parameters:

seq - the CharSequence to check (may be null)

Returns:

true if the CharSequence is not empty and contains at least 1 whitespace character

It handles empty and null parameters and provides the functionality at a central place.

score 0 · Answer 6 · answered Aug 08 '12 at 11:28

0

From sun docs:

\s A whitespace character: [ \t\n\x0B\f\r]

The simplest way is to use it with regex.

answered Aug 08 '12 at 11:28

MByD

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The *only* way to use `\s` is with a regular expression. – user207421 Dec 01 '16 at 10:26

doxmoxbox · Answer 7 · 2015-07-13T08:06:49.793

0

boolean whitespaceSearchRegExp(String input) {

    return java.util.regex.Pattern.compile("\\s").matcher(input).find();

}

edited Jul 13 '15 at 08:06

answered Jul 12 '15 at 10:33

doxmoxbox

11
3

2

Welcome on SO. Please check the guideline to give a good answer. http://stackoverflow.com/help/how-to-answer – codingadventures Jul 12 '15 at 10:51

score 0 · Answer 8 · edited Dec 01 '16 at 11:10

0

Why don't you check if text.trim() has a different length? :

if(text.length() == text.trim().length() || otherConditions){
    //your code
}

edited Dec 01 '16 at 11:10

Wai Ha Lee

8,598
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answered Dec 01 '16 at 10:06

Adrián José Zapater

11

Because it creates another `String`, for a start. – user207421 Dec 01 '16 at 10:27

Whitespaces in java

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