How to strip "control characters" from a CharSequence?

Question

I have CharSequence source, int start, int end

I would like to strip all "control characters" from source between start and end and return this as a new CharSequence

by "control character" I mean undeseriable characters like Tab and Return, line feeds and such... basically all that was in ASCII < 32 (space) ... but I don't know how to do it in this "modern age"

what is a char? is it unicode? How can I remove these "control characters" ?

Have you checked this: http://stackoverflow.com/questions/4283351/how-to-replace-special-characters-in-a-string — assylias, Feb 23 '12 at 16:46
Use [`String#replaceAll()`](http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#replaceAll%28java.lang.String,%20java.lang.String%29). — Matt Ball, Feb 23 '12 at 16:48

score 2 · Answer 1 · answered Feb 23 '12 at 17:12

You could use CharSequence.subSequence(int, int) and String.replaceAll(String, String) as follows:

source.subSequence(0, start).toString() + source.subSequence(start, end).toString().replaceAll("\\p{Cntrl}", "") + source.subSequence(end, source.length()).toString()

Sergey Kalinichenko · Accepted Answer · 2012-02-23T17:02:04.703

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Assuming that you can get the whole source into memory, you can do this:

String tmp = source.toString();
String prefix = tmp.substring(0, start-1);
String suffix = tmp.substring(end+1);
String middle = tmp.substring(start, end).replaceAll("\\s", "");
CharSequence res = prefix + middle + suffix;

edited Feb 23 '12 at 17:02

answered Feb 23 '12 at 16:47

Sergey Kalinichenko

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How does this do anything with control characters? – Highland Mark Feb 23 '12 at 16:56
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@HighlandMark OP calls "control characters" what's commonly known as "whitespace" (by "control character" I mean undesirable characters like Tab and Return, line feeds and such...); `replaceAll()` removes all such characters from the beginning and from the end of a string. – Sergey Kalinichenko Feb 23 '12 at 17:00
Thanks for the clarification. – Highland Mark Feb 23 '12 at 20:27
Converting a CharSequence to a String will remove any special formatting (for instance bolded characters). – Aaron Oct 04 '16 at 16:06

score 1 · Answer 3 · edited Jun 28 '19 at 13:37

1

Use Character.isISOControl(char) if using latest Guava library.
Yes char is Unicode.

edited Jun 28 '19 at 13:37

speksy

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answered Feb 23 '12 at 16:49

Highland Mark

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score 1 · Answer 4 · answered Feb 23 '12 at 18:10

1

Using Guava's CharMatcher:

return CharMatcher.JAVA_ISO_CONTROL.removeFrom(string);

answered Feb 23 '12 at 18:10

Louis Wasserman

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example does not compile in latest guava library. – speksy Jun 28 '19 at 12:25

How to strip "control characters" from a CharSequence?

4 Answers4