Remove doubled letter from a string using java

Question

I need to remove a doubled letter from a string using regex operations in java. Eg: PRINCEE -> PRINCE APPLE -> APLE

Answer 1

If you want to replace just duplicate ("AA"->"A", "AAA" -> "AA") use

public String undup(String str) {
  return str.replaceAll("(\\w)\\1", "$1");
}

To replace triplicates etc use: str.replaceAll("(\\w)\\1+", "$1");

To replace only a single dupe is a long string (AAAA->AAA, AAA->AA) use: str.replaceAll("(\\w)(\\1+)", "$2");