Conversion of JAD file to APK is possible using a dedicated JAD/JAR tp APK converter. Provided you have valid JAD file and a relevant JAR archive with the app data.
Convert Java application descriptor to Google Android application package.
We have found one software suitable in our database for this conversion.
On-line services software - convert jad to apk on web
Online Service used to convert JAR archives to Android APK packages.
Convert from jad file
to apk file
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.