Removing repeated characters in String

Question

I am having strings like this \"aaaabbbccccaaffffddcfggghhhh\" and i want to remove repeated characters get a string like this \"abcadcfgh\".

A simplistic implementati

Answer 1

You can do this:

"aaaabbbccccaaffffddcfggghhhh".replaceAll("(.)\\1+","$1");

The regex uses backreference and capturing groups.

The normal regex is (.)\1+ but you've to escape the backslash by another backslash in java.

If you want number of repeated characters:

String test = "aaaabbbccccaaffffddcfggghhhh";
System.out.println(test.length() - test.replaceAll("(.)\\1+","$1").length());

Demo