Create a Java .jar file from class files
Applies to: 
SQL Server 2019 (15.x) and later versions
Learn how to package your class files into a .jar file, when using SQL Server Language Extensions to execute Java code. We recommend you package your files.
Create a .jar file
To create a .jar from class files, navigate to the folder containing your class file and run this command:
jar -cf <MyJar.jar> *.class
Make sure the path to jar.exe is part of the system path variable. Alternatively, specify the full path to jar which can be found under /bin in the JDK folder. For example:
C:\Users\MyUser\Desktop\jdk1.8.0_201\bin\jar -cf <MyJar.jar> *.class