A recently opened file list containing menu in pdf reader will be a nice feature in PDF reader.
I've made a patch for this. A new package under org.apache.pdfbox.tools is created named util which contains the class RecentFiles so that this can be used in feature improvement of other GUI tools PDFBox provides.
In RecentFiles class, file path string is saved in preference by converting and breaking them into byte array. To do That, I've followed this post .
I'm saying this to help PDFBox to make an informed decision concerning licences issues if there is any.