To send errors to Rollbar from your Java application, you should use our rollbar-java package.
compile('com.rollbar:rollbar-java:1.0.0')
If your web server is implemented as a Servlet, you can configure and enable Rollbar entirely within your WEB-INF/web.xml file using rollbar-web:
<?xml version="1.0" encoding="UTF-8"?>
<web-app ...>
<!-- Rollbar listener and filter -->
<listener>
<listener-class>com.rollbar.web.listener.RollbarRequestListener</listener-class>
</listener>
<filter>
<filter-name>Rollbar Filter</filter-name>
<filter-class>com.rollbar.web.filter.RollbarFilter</filter-class>
<init-param>
<param-name>access_token</param-name>
<param-value>[{{ server_access_token }}]</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>Rollbar Filter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<!-- Servlets -->
<servlet>
<servlet-name>hello</servlet-name>
<servlet-class>com.yourdomain.yourapp.servlet.HelloRollbarServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>hello</servlet-name>
<url-pattern>/hello</url-pattern>
</servlet-mapping>
</web-app>
rollbar-web exposes a request listener and a filter which can be used to report all errors that occur during the request lifecycle to Rollbar. You can see a rollbar-web example on GitHub.
All configuration is done via the Config object in rollbar-java. You can see the interface here.