yaz4j is a toolkit for Java which includes a wrapper for the ZOOM API of YAZ. This allows developers to write Z39.50/SRU clients in Java. yaz4j supports both search and scan. See the javadoc for details.
yaz4j was initially implemented by Talis and is now maintained and developed by Index Data.
For a tutorial on how to use yaz4j in a servlet environment please see Building Simple HTTP–Z3950gateway using yaz4j and Tomcat.
For Windows users: yaz4j is now part of the YAZ Windows installer and this is the recommended way of obtaining yaz4j on that platform.