Re: ClassLoader not loading recompiled classes

From:

"Aryeh M. Friedman" <Aryeh.Friedman@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 03 Oct 2007 22:46:38 -0000

Message-ID:

<1191451598.155608.312460@19g2000hsx.googlegroups.com>

        while (true) {
            long lastMod = classFile.lastModified();
            if (lastMod > classTimestamp) {
                // if classfile is new, load it.
                System.out.println("(re)loading MessageGeneratorImpl");
                Object o = new URLClassLoader(
                        new URL[] {new File("../generator").toURL()},
                        Reloader.class.getClassLoader()).
                            loadClass("MessageGeneratorImpl").newInstance();
                generator = (MessageGenerator)o;
                classTimestamp = lastMod;
            }

            System.out.println("message: " + generator.getMessage());
            Thread.currentThread().sleep(10 * 1000);
        }

This is functionally identical to the following (which is the test
code that lead me to make the comment about externally compiled
classes):

while(true) {
    testClassLoader(); // create a new class loader and load class

    System.out.println("hnit any key to reload");
    System.in();
}

new timestamps *DO NOT* help.... the only solution I have found is to
read the binary class file and then link it to symbol table with
ClassLoader.defineClass (btw this is the solution JUnit uses)).