I was searching for a Java version of the Tumblr API but was unable to find one, so decided to write a simple API.
TumbleJ is a simple Java class that presently writes a text post to tumblr. It creates a HTTP POST based on the Tumblr API parameters and posts it to Tumblr. Tags can also be set. The code and docs are available here.
I might add methods for the other type of posts (audio etc), if time permits.
Update: I’ve released a new version of TumbleJ with more features. Details here