Question

I´m trying to add a plugin system to my app. I have an abstract class that plugins must extend. This class provide usuful methods so I really need it. The problem is that these plugins could be written by anyone so I suppouse that they’ll need the abstract class code to be able to compile their code.

I don´t want to complicate the process of creating a plugin. Is there a way to compile the code without know the abstract class body (only its methods)?

Thanks in advance.

Answer 1

Is there a way to compile the code without know the abstract class body (only its methods)?

No. In order to to compile a class declared as

class A extends B

you’ll have to have B in source format in the source path or in .class format on the class path.

(If knowing only the methods is sufficient for writing the plugin, it sounds more like you’re after an interface than an abstract class.)

I don´t want to complicate the process of creating a plugin.

Providing the compiled .class file of B is completely uncomplicated and probably the best practice in this scenario.

Actually, having an API at hand through a .jar-file containing the relevant classes and interfaces is probably the standard.

To be clear:

1. Take the classes that are relevant for plugin-development, compile them, and put them in, say pluginapi.jar
2. Distribute the .jar and tell plugin developers that their plugins should compile, provided the pluginapi.jar
3. Ask the plugindevelopers to provide you with plugin.jar (not necessarily including pluginapi classes)
4. In your application, make sure that the plugin API classes are present, for instance by including them the class path.
5. Load the plugin classes.