By default, the System.out and System.err output of servlets are sent to the server log, and during startup, server log messages are echoed to the System.err output. Also by default, there is no Windows-only console for the System.err output.
You can change these defaults using the Admin Console. In the developer profile, select the Application Server component and the Logging tab. In the cluster profile, select the Logger Settings component under the relevant configuration. Then check or uncheck Write to System Log. If this box is checked, System.out output is sent to the server log. If it is unchecked, System.out output is sent to the system default location only.
For more information, click the Help button in the Admin Console from the Logging page.