In Java regexps, the dot matches a code point or an unpaired surrogate, so if you have a proper surrogate pair, the dot matches the whole pair without splitting

In Java regexps, the dot matches a code point or an unpaired surrogate, so if you have a proper surrogate pair, the dot matches the whole pair without splitting it. It does split grapheme clusters. It's unclear to me what you mean by "Java Characters". A Java char is a UTF-16 code unit, and the java.lang.Character boxes a char (16 bits unsigned). However, since Java 5, java.lang.Character has static methods for astral-aware UTF-16 operations where a code point is a Java int (32 bits signed).