First you should define a printer and a container for the printer setting
PrintService printService = PrintServiceLookup
.lookupDefaultPrintService(); //use the default printservice, for testing purposes it makes sense to use a virtual printer!
PrintRequestAttributeSet attributes = new HashPrintRequestAttributeSet();
Now you can add the printer settings
attributes.add( MediaSizeName.ISO_A4 );
attributes.add( OrientationRequested.PORTRAIT );
Now you’re read to print the result
new PDFComparer()
.addPresenter( new DifferencesPrintPresenter( printService, attributes ) )
.compare( <file1>, <file2> );