Google Checkout Java SDK is a free and open-source utility that provides a Java SDK that developers can use to integrate Google Checkout APIs in their web-applications.
Google Checkout Java SDK gives developers convenient Java based handlers to deal with the XML messages sent by the Google Checkout APIs notifications and callbacks.
Google Checkout Java SDK is a cross-platform utility capable of running on any operating system that comes with Java support (e.g. Mac OS X, Windows, Linux).
Detailed instructions on how to install and use the Google Checkout Java SDK utility on your Mac are available HERE.