Java Class Loader
.jaddClassPath adds directories or JAR files to the class
path.
.jclassPath returns a vector containing the current entries in
the class path
.jaddClassPath(path, class.loader=.rJava.class.loader) .jclassPath(class.loader=.rJava.class.loader) .jclassLoader(package=NULL)
path |
character string vector listing the paths to add to the class path |
class.loader |
Java class loader to use for the query of madification. Defaults to global class loader. |
package |
string, name of a package or |
Whenever a class needs to be instantiated in Java it is referred by name which is used to locate a file with the bytecode for the class. The mechanism to map a name to an actual bytecode to load ind instantiate is habdled by the Java class loader. It typically keeps a list of directories and JAR files to search for the class names.
The .jaddClassPath() function allows the user to append new
locations to the list of places which will be searched. The function
.jclassPath retrieves the current sarch list from the loader.
When rJava is initialized, it instantiates the global class loader
which is responsible for finding classes in functions such as
.jnew(). In addition to the global class loader, R packages can
create their own class loaders to avoid conflicts between packages
such that they can be sure to use their own files to look for
classes. See .jpackage for details on how that works.
If the package argument is supplied .jclassLoader will
look in that package to see if it has a custom loader and will return
it, otherwise it returns the global loader. Note that is will fail with
an error when supplied a non-existing package name.
If you want to trace issues related to missing classes, you can enable
debugging in the class loader by using the setDebug method, for
example: .jclassLoader()$setDebug(1L)
.jclassPath returns a character vector listing the class path sequence.
## Not run:
.jaddClassPath("/my/jars/foo.jar","/my/classes/")
print(.jclassPath())
## End(Not run)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.