Java Class.isAssignableFrom ALWAYS returning false... only outside IDE

Question

I've tested on three windows machines, and two linux VPSes, on different versions of Java, both on the OpenJDK & Oracle JDK. It functioned perfectly, and then all of a sudden, it only works in my IDE, though I haven't changed any relevant code, and I can't imagine what can cause this.

Prevalent code in system:

Class<?> cls = (session == null ? secjlcl : session.getJLCL()).loadClass(name);
Logger.log(JavaLoader.class.isAssignableFrom(cls) + " - " + cls + " - " + cls.getSuperclass().getName());
if (JavaLoader.class.isAssignableFrom(cls)) {

And my ClassLoader:

public class JavaLoaderClassLoader extends URLClassLoader {
public JavaLoaderClassLoader(URL[] url, ClassLoader parent) {
    super(url);
}

private HashMap<String, Class<?>> javaLoaders = new HashMap<String, Class<?>>();

public String addClass(byte[] data) throws LinkageError {
    Class<?> cls = defineClass(null, data, 0, data.length);
    javaLoaders.put(cls.getName(), cls);
    return cls.getName();
}

public Class<?> loadClass(String name, boolean resolve) {
    if (javaLoaders.containsKey(name)) return javaLoaders.get(name);
    try {
        Class<?> see = super.loadClass(name, resolve);
        if (see != null) return see;
    }catch (ClassNotFoundException e) {
        Logger.logError(e);
    }
    return null;
}

public void finalize() throws Throwable {
    super.finalize();
    javaLoaders = null;
}
}

One note, I expect many classloaders to load a different file in the same name/package, so I use separate classloaders to keep them separate, however in testing, that was NOT tested.

Now, this had worked flawlessly in the past, and I have zero clue why it stopped. I would assume I broke something, but the code still works in my IDE?

Answer 1

This appears to be your bug:

public JavaLoaderClassLoader(URL[] url, ClassLoader parent) {
    super(url);
}

You aren't installing parent as the parent class loader through the super constructor.