At times, requirement to update an already delivered JAR file will need to be handled. Of course, JAR file is a way of packaging and delivering Java class file and related metadata files in a package. But having an easier way is always welcome by the developer group.
The following command when executed on a command line will achieve updating a JAR file with 1 or more files as needed
jar uf jar-file input-file-name(s)
uf : indicates update and file
jar-file : the jar file that needs to be updated
input-file-name(s) : the name of file(s) that needs to be updated in the jar file.