Java difference StdOut vs System.out.println

I just started working on java as I loaded the eclipse and created a java project. The project worked fine, then I imported the class, but it does not work due to the following lines

StdOut.println(p + "  " + q);

after searching i replaced it with

System.out.println(p + "  " + q);

the same path for input.

I tried to import system.io.*did not work. then I tried it import StdIndidn’t work

As I understand it, this may be due to another project template / type. and tutorial links will also be helpful. Thanks