Java 9, compatability issue with ClassLoader.getSystemClassLoader

Question

The following code adds jar file to the build path, it works fine with Java 8. However, it throws exception with Java 9, the exception is related to the cast to URLClassLoad

Answer 1

There's also this guys article that helped me. I could not find the article but... here: https://github.com/CGJennings/jar-loader

Here's a part of guide inside there there's a jar at release you could read his guide & setup it up.

I just tried it myself download the jar file which include the class file

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.lang.instrument.Instrumentation;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.jar.JarFile;

public final class classname{

    public static void premain(String agentArgs, Instrumentation instrumentation) {
        loadedViaPreMain = true;
        agentmain(agentArgs,instrumentation);
    }

    public final static void addToClassPath(File jarfile)throws IOException{inst.appendToSystemClassLoaderSearch(new JarFile(jarfile));}
    public final static void agentmain(String agentArgs, Instrumentation instrumentation) {
      if (instrumentation == null){throw new NullPointerException("instrumentation");}
      if (inst == null) {inst = instrumentation;}
    }
    private static Instrumentation inst;
    private static boolean loadedViaPreMain = false;
}

I just try it out myself package these code as a package then start the application class with -javaagent:plugin......jar option then call this function.It doesn't change my classpath.I am probably missing some details here.

Hope you can make it work though.