One of the administrative tasks that you perform during the development of Java external routines (UDFs and external stored procedures) is JAR or ZIP file registration and distribution, as discussed in Registering the JAR or ZIP File.
If the Java source code that implements an external routine changes, you must perform another administrative task: JAR or ZIP file replacement. To replace a previously registered JAR or ZIP file, use the SQLJ.REPLACE_JAR external stored procedure. For details on using SQLJ.REPLACE_JAR to replace a JAR or ZIP file, see Replacing Registered JAR or ZIP Files.
For information on other administrative tasks that you perform during the development or maintenance of Java external routines, see Administration.