How to remove specific repeated characters from text?

Question

I have a String like

"this is line 1\n\n\nthis is line 2\n\n\nthis is line 3\t\t\tthis is line 3 also"

What I want to do is remove repeated specific characters like "\\n", "\\t" from this text.

"this is line 1\nthis is line 2\nthis is line 3\tthis is line 3 also"

I tried some regular expressions but didn't work for me.

text = text.replace("/[^\\w\\s]|(.)\\1/gi", ""); 

Is there any regex for this?

Answer 1

If you need to only remove sepcific whitespace chars, \\s won't help as it will overmatch, ie it will also match spaces, hard spaces, etc.

You may use a character class with the chars, wrap them with a capturing group and use a backreference to the value captured. And replace with the backreference to the Group 1 value:

.replaceAll("([\n\t])\\1+", "$1")

See the regex demo .

Details

• ([\\n\\t]) - Group 1 (referred to with \\1 from the pattern and $1 from the replacement pattern): a character class matching either a newline or tab symbols
• \\1+ - one or more repetitions of the value in Group 1.

Answer 2

我会用番石榴的CharMatcher ：

CharMatcher.javaIsoControl().removeFrom(myString)