We have found one software suitable in our database for this conversion.
Although you can re-pack Java archives (.jar) to Debian archives (.deb) in almost any file manager today, the conversion itself would serve no purpose as Debian accepts only specially formatted archives for its installation packages.
However you may find a special tools that allow users to create Debian app installation packages from a Java app stored in an executable .jar file. But generally, this is work for a programmer.
JAR
Files with jar extension are compressed archives, typically used for content in Java and distribution/installation purposes.
DEB
Files with deb extension can be mainly found as Debian distribution packages - compressed archives for Debian Linux operating system. Some archiving utilities, such as 7-zip, are also able to extract the content of DEB packages.