package com.company;


import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Arrays;

public class ClassManager {
    private final String classDir;

    public ClassManager(String classDir) {
        this.classDir = classDir;
    }

    public MyClass load(String classDirName, String className) {
        URL[] urls = new URL[0];
        File file = new File(classDir + "/" + classDirName);

        try {
            URL url = file.toURI().toURL();
            urls = new URL[]{url};
            System.out.println(Arrays.toString(urls));
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }

        URLClassLoader loader = new URLClassLoader(urls, getClass().getClassLoader()) {
            @Override
            public Class<?> loadClass(String name) throws ClassNotFoundException {
                System.out.println(name);

                Class<?> clazz = null;
                if (name.startsWith("com.company") || name.startsWith("java")) clazz = super.loadClass(name);
                try {
                    if (clazz == null) clazz = findClass(name);
                } catch (ClassNotFoundException e) {
                    clazz = super.loadClass(name);
                }
                return clazz;
            }

        };

        try {
            return (MyClass) loader.loadClass(className).newInstance();
        } catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
            e.printStackTrace();
        }
        return null;
    }
}

package com.company;

public class Main {

    public static void main(String[] args) {
        ClassManager pm = new ClassManager("E:/test");
        pm.load("class1", "myCls");
        pm.load("class2", "myCls");
    }
}