No printing to System.out or System.err will appear in the Debug Log window if the method is called from the Java Shell window, where the output already goes to that window,
You can control the visibility of the Debug Log window using the Debug Log () button in the Method ribbon tab. In the Debug Log window, select the Scroll Lock button () to prevent new messages from being scrolled into view, useful in case you are inspecting some part of the log while new messages are being added.