Best approach to dynamically load modules (classes) in Java

Question

I\'m currently writing an application that requires to operate on different type of devices. My approach would be to make a \"modular\" application that can dynamically load dif

Answer 1

Additionnaly to the ServicerLoader usage given by @SeverityOne, you can use the module-info.java to declare the different instanciation of the interface, using "uses"/"provides" keywords.

Then you use a module path instead of a classpath, it loads all the directory containing your modules, don't need to create a specific classLoader

The serviceLoader usage:

public static void main(String[] args) {
    ServiceLoader sl = ServiceLoader.load(IGreeting.class);
    IGreeting greeting = sl.findFirst().orElseThrow(NullPointerException::new);
    System.out.println( greeting.regular("world"));
}

In the users project:

module pl.tfij.java9modules.app {
    exports pl.tfij.java9modules.app;
    uses pl.tfij.java9modules.app.IGreeting;
}

In the provider project:

module pl.tfij.java9modules.greetings {
    requires pl.tfij.java9modules.app;
    provides pl.tfij.java9modules.app.IGreeting
            with pl.tfij.java9modules.greetings.Greeting;
}

And finally the CLI usage

java --module-path mods --module pl.tfij.java9modules.app

Here is an example; Github example (Thanks for "tfij/" repository initial exemple)

Edit, I realized the repository already provides decoupling examples: https://github.com/tfij/Java-9-modules---reducing-coupling-of-modules