Writing a Tool that depends on a Library

in Library and Tool Development • 2 years ago

I've just written a processing library, and now I'm trying to write a tool that depends on the library (i.e., the tool uses some of the classes in the library's .jar file). I'm having trouble. The tool compiles successfully, but problems come up when I try to launch Processing. The Tool complains that it can't find the library classes (it throws a ClassNotFoundException).

I've tried including this line in build.properties --

classpath.libraries.location=${sketchbook.location}/libraries

-- but that doesn't seem to help.

How can I tell the Tool to look for classes in Processing's library folder?

Any suggestions?

Apologies if I'm forgetting to do something obvious. I'm new-ish to Java.

Many thanks,

Replies(2)

PhiLho

Re: Writing a Tool that depends on a Library

2 years ago

You probably need to put a copy of the jar of your library in the tools folder of your sketchbook as well. Duplicating files isn't nice but see this as a workaround until a better answer is given...

d_h_benson

Re: Writing a Tool that depends on a Library

2 years ago

Hi,

Phi.lho, thanks again for your workaround. For the benefit of anyone else who stumbles on this thread, I've found a second workaround as well.

It's possible to change the java classpath at runtime. What I've ended up doing is adding my library to the classpath before I try to instantiate any objects from it.

To add a file to the classpath, you can use the ClassPathHacker code found here:

http://forums.sun.com/thread.jspa?threadID=300557&start=45&tstart=0

That includes a method called addFile(File f) that takes the file to add as a parameter. You can get the current location of the Processing Library folder from a call to processing.app.Base.getSketchbookFolder().

The complete solution looks something like this (assuming you've imported processing.app.*):

String myLibraryName = "myLibrary";

File librariesFolder = new File(Base.getSketchbookFolder(),"libraries"); //Sketchbook/libraries

File myLibraryFolder = new File(librariesFolder,myLibraryName); //Sketchbook/libraries/"myLibraryName"

File myLibrarySubFolder = new File(myLibraryFolder,"library"); //Sketchbook/libraries/"myLibraryName"/library

File myLibraryJar = new File(myLibrarySubFolder,myLibraryName+".jar"); //Sketchbook/libraries/"myLibraryName"/library/"myLibraryName".jar

ClassPathHacker.addFile(myLibraryJar);

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