I would like to extract the date a jpg file was created. Java has the lastModified method for the File object, but appears to provide no support for extracting the created date
I use this metadata library: http://www.drewnoakes.com/code/exif/
Seems to work pretty well, although bear in mind that not all JPEG images have this information, so it can't be 100% fool-proof.
If the EXIF metadata doesn't contain the created date, then you'll probably have to make do with Java's lastUpdated - unless you want to resort to Runtime.exec(...) and using system functions to find out (I wouldn't recommend this, though!)