When a line contains a lot of text then I have observe the following:
Word Wrap: None - works exactly as expected, long lines are displayed on one long line
Word Wrap: Soft - breaks lines where there is a space character, which is as I would expect
Word Wrap: Hard - initially looks like None but after "Format Paragraph" looks like soft, looks like a bug
Changes made using Buffer Options.
I would expect Hard to wrap at 80 characters irrespective to space characters etc.
Selecting Hard mode and then "Format Paragraph" marks the file as Edited which is not what I would expect having typed nothing.
Using jEdit 4.3 Pre 8