These topics discuss saving and loading J objects (in object-oriented sense and otherwise), individually or in groups, a technology also known as "persistence" or "serialization".
Regular Files
files: file access utilities, Base Library
1!:n Files (foreign), Dictionary
Files, J Primer
Special File Formats
csv: read/write comma-separated value data (*.csv) files, Base Library
csv: read/write comma-separated value data (*.csv) files, tables/csv addon
zip file utilities, arc/zip addon
Wave (*.wav) audio file, media/wav addon
Image (*.gif, *.jpg, *.png, etc) files, media/platimg addon
File Workspace
Workspaces in older J by Raul Miller, Why were workspace removed from J7.0 in comp.lang.apl, 1994-01-18
J-file Workspace by Eke van Batenburg, Workspace in J in comp.lang.apl, 1997-03-24
WS Files script by OlegKobchenko, based on J-file Workspace.
Object Stream, costream script by OlegKobchenko
Object per File
By Devon McCormick, File J Variables (originally Utility contribution: WS.ijs - var->file, file->var in JForum, 2003-07-12)
Component Files
Component files, Primer
Component Files (jfiles), J User Guide
jfiles: component file definitions, Base Library
Keyed Files
Keyed Files (keyfiles), J User Guide
keyed-file definitions, Base Library
Memory-Mapped Files
Mapped Files, Lab
Memory Mapped Files in J, Papers
Mapped Boxed Arrays, Release Notes
jmf: mapped files, Base Library
See Also
Data Files, Learning J
Input And Output, J for C Programmers