How would I fix this classloader issue?

Question

Let me start off by saying I'm not the best at Java so I may have missed something really simple...

I'm working on a plugin system and everything works perfectly fine in eclipse but not when I actually launch the applet outside of it.

I'm trying to load a .class file from a directory and execute it, I know why it isn't working I just don't know what to do to solve it.

The issue is that Eclipse is referencing the applet itself in the class-path but it's not being referenced in the class-path outside of eclipse and I don't have access to -cp or -classpath, I can only launch it via a launcher designed to load the jar with a fixed class-path.

Any ideas on how I would be able to solve this issue?

Loader Code:

final ClassLoader loader = new URLClassLoader(new URL[] { new File("C:/Plugin/Directory/").toURI().toURL() });
final Class<?> c = loader.loadClass("PluginFile");
Object s = c.newInstance();
s.getClass().getMethod("onLoad").invoke(s);

Plugin Code:

import net.plugintest.pluginsystem.*;

public class PluginFile extends ClientPlugin
{
    private String Author = "Plugin Author";
    private String Description = "Plugin Description"
    private Player p = new Player();

    @Override
    public void onLoad() 
    {
        p.talk("Testing");
    }
}

This problem has been driving me up the wall for a week now, I don't know what to do. :/

Use the URLClassLoader to Load the class that you want on your classpath too refer : http://stackoverflow.com/questions/252893/how-do-you-change-the-classpath-within-java — Mukul Goel, Oct 08 '12 at 07:53
`java.lang.ClassNotFoundException: net.plugintest.pluginsystem.ClientPlugin` — user1728017, Oct 08 '12 at 10:25

score 3 · Accepted Answer · answered Oct 08 '12 at 07:59

3

I'm not sure but try providing parent classloader to the classloader you create, eg:

ClassLoader parent = Thread.currentThread().getContextClassLoader();
// or
// ClassLoader parent = getClass().getClassLoader();
ClassLoader loader = new URLClassLoader(new URL[] { new File("C:/Plugin/Directory/").toURI().toURL() }, parent);

answered Oct 08 '12 at 07:59

Adam Dyga

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Nope, I'm still getting `java.lang.ClassNotFoundException: net.plugintest.pluginsystem.ClientPlugin` :/ – user1728017 Oct 08 '12 at 10:23
Ahh i feel like a derp. Your answer helped me, instead of `Thread.currentThread().getContextClassLoader()` i used `ClientPlugin.class.getClassLoader()` and it solved my problem. :P – user1728017 Oct 08 '12 at 10:38

How would I fix this classloader issue?

1 Answers1