I've just released Pinboard Poster, a small Kotlin/Java library for posting to Pinboard.

Kotlin

val poster = PinboardPoster("user:TOKEN")
poster.addPin("http://www.example.com/foo", "This is a test")
poster.deletePin("http:///www.example.com/bar")

Java

final PinboardPoster poster = new PinBboardPoster("user:TOKEN");
poster.addPin("http://www.example.com/foo", "This is a test");
poster.deletePin("http:///www.example.com/bar");

Pretty basic. I needed something to replace del.icio.us since it no longer has a functional API.

As usual documentation and source are on GitHub.