Regex - Replace strings containing only one but repeating char

Question

I want to replaceAll strings like:

"aaaa"
"zzzzzzz"
"----------"
"TTTTTT"
"...."

String contains only one char, but > 3 times.

I use Java. I can replace a specific char (like "a") with more than 3 times, but don't know how to do this with any char:

str = str.replaceAll("^[a]{4,}$", "");

Any idea? If this can't be done in regex, how would you do it?

Any char? Use "(?s)^(.)\\1{3,}$".

Wiktor Stribiżew
– Wiktor Stribiżew

2015-11-26 10:56:32 +00:00
Commented Nov 26, 2015 at 10:56 — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Nov 26, 2015 at 10:56
Seems to work, thanks! :-) Can you please explain it?

dynobo
– dynobo

2015-11-26 11:03:39 +00:00
Commented Nov 26, 2015 at 11:03 — dynobo
– dynobo, Commented Nov 26, 2015 at 11:03

Wiktor Stribiżew · Accepted Answer · 2015-11-26 10:58:40Z

3

Any char can be matched with . and Pattern.DOTALL modifier.

To check if it is the same, we can capture the first character and use a backreference to match the same text, and a limiting quantifier {3,} to check for at least 3 occurrences of the same substring.

See a regex and IDEONE demo:

List<String> strs = Arrays.asList("aaaa", "zzzzzzz", "----------", "TTTTTT", "....");
for (String str : strs)
    System.out.println("\"" + str.replaceAll("(?s)^(.)\\1{3,}$", "") + "\"");

answered Nov 26, 2015 at 10:58

Wiktor Stribiżew

631k41 gold badges502 silver badges632 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Regex - Replace strings containing only one but repeating char

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related