Q:

Appending a codepoint to a java.lang.Appendable

java.lang.Appendable supports append(char) but not appendCodepoint(int).
Is there any efficient way (no object creation) using the standard libraries to append a codepoint to an Appendable that works with supplemental codepoints?
I'd rather not roll my own UTF-16 encode function, and everything in java.lang.Character requires mucking around with char[]s.

A:

I mean, it sounds like what you want is just to do Character.toChars(int) without the array overhead, right?  Here's the source of Character.toChars; it's not particularly complicated to replicate yourself.

