Redirecting System.out.println lines to either the server log or to a file on the server

I have an application that runs fine on Windows 7 (embedded Weblogic server in JDeveloper), but when the app is deployed to Solaris, it can't find the files that app needs to start running.

I put in System.out.println lines to show me what was happening, and expected to see them in the server log. They are not there, and I need to know how to configure Weblogic 11g to redirect System.out.println lines either to the server log, or to a file on the server.