Dynamic execution is not working when the plugin was installed

Question

I am developing an Eclipse plugin that runs the current active file. I am using this method

public static void runIt(String fileToCompile,String packageName) throws ClassNotFoundException, IllegalArgumentException, IllegalAccessException, InvocationTargetException, InstantiationException, SecurityException, NoSuchMethodException
    {

        File file = new File(fileToCompile);

        try
        {
            // Convert File to a URL
            URL url = file.toURL(); // file:/classes/demo
            URL[] urls = new URL[] { url };

            // Create a new class loader with the directory
            ClassLoader loader = new URLClassLoader(urls);

            ClassLoader classLoader = Thread.currentThread()
                    .getContextClassLoader();

            Class<?> thisClass = classLoader.loadClass("NewFile");
            Object newClassAInstance = thisClass.newInstance();
            Class params[] = new Class[1];
            params[0]=String[].class;
            Object paramsObj[] = {};
            String m=null;
            Object instance = thisClass.newInstance();
            Method thisMethod = thisClass.getDeclaredMethod("main", params);
            String methodParameter = "a quick brown fox";
            // run the testAdd() method on the instance:
            System.out.println((String)thisMethod.invoke(instance,(Object)m));



        }
        catch (MalformedURLException e)
        {
        }

    }

But it works when I "Launch Eclipse application" [run the plugin in another Eclipse window] but when I installed the plugin in Eclipse it doesn't work anymore. The problem is in this line

Class thisClass = classLoader.loadClass("NewFile"); It cannot find the class to be executed

What does `packageName` signify ? – Vishal K Jun 16 '13 at 21:00 — Vishal K, Jun 16 '13 at 21:00

score 0 · Answer 1 · answered Jun 23 '13 at 05:29

I would assume that the context classloader is different when running as a plugin. Look at the classloader hierarchy obtained in your line:

ClassLoader classLoader = Thread.currentThread().getContextClassLoader();

See if it differs in the two runtime contexts. If you can step-debug the plugin, you should be able to explore around the available objects and find a classloader among them that works for your dynamic class.

If you want to use a URLClassLoader (which appears to have been abandoned in your code), you need to give it a parent, like:

new URLClassLoader(urls, this.getClass().getClassLoader())

Dynamic execution is not working when the plugin was installed

1 Answers1