Loading classes that are not in the classpath

Question

Say I compiled a Groovy script using Groovyc, which generated one or more .class files on a file system. From a Java application, how can I add these classes to the classpath dynamically to load them and call their methods? The goal is to precompile Groovy scripts and save them in a database, so evaluation can be done from compiled versions of scripts.

Answer 1

You can create an instance of URLClassLoader to load new classes from the directory:

URL dirUrl = new URL("file:/" + "path_to_dir" + "/");             // 1
URLClassLoader cl = new URLClassLoader(new URL[] {dirUrl},
                             getClass().class.getClassLoader());  // 2
Class loadedClass = cl.loadClass("com.xyz.MyClass");
MyClass obj = (MyClass) loadedClass.newInstance();
obj.doSomething();

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Answer 2

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