You must load resource files using the loadjava tool. If you create .class files outside the database with a conventional compiler, then you must load them with the loadjava tool. The alternative to loading class files is to load source files and let Oracle Database compile and manage the resulting class schema objects. In Oracle Database 12c Release 1 (12.1), the most productive approach is to compile and debug most of your code outside the database, and then load the .class files. For a particular Java class, you can load either its .class file or the corresponding .java file, but not both.

The loadjava tool accepts Java Archive (JAR) files that contain either source and resource files or class and resource files. When you pass a JAR or ZIP file to the loadjava tool, by default, it opens the archive and loads its members individually.

A file, whose content has not changed since the last time it was loaded, is not reloaded. As a result, there is little performance penalty for loading JAR files. Loading JAR files is a simple, fool-proof way to use the loadjava tool.

It is illegal for two schema objects in the same schema to define the same class. For example, assume that a.java defines class x and you want to move the definition of x to b.java. If a.java has already been loaded, then the loadjava tool will reject an attempt to load b.java. Instead, do either of the following:

• Drop a.java, load b.java, and then load the new a.java, which does not define x.

• Load the new a.java, which does not define x, and then load b.java.