CatchAPI is a Java library for Android. It makes it easy to use the Catch.com REST API. Here's a quick preview...
CatchAPI api = new CatchAPI("MyCoolApp", context);
// sign in
api.signIn("username", "pass1234", null);
// add a new note
CatchNote note = new CatchNote();
long timestamp = System.currentTimeMillis();
note.creationTime = timestamp;
note.modificationTime = timestamp;
note.text = "Hello World!";
api.addNote(note);
Check out the library documentation for more. The CatchAPI class is the primary interface, so you might want to start there.
Also, take a look at the Example app to see an example of the library in use. The interesting stuff is in Dashboard.java, mostly near the bottom of the file.