ClassLoader loader = new ClassLoader() {
	@Override
	protected Class<?> findClass(String name) throws ClassNotFoundException {
		InputStream in = null;
		try {
			in = new BufferedInputStream(new FileInputStream(filename));
			ByteArrayOutputStream byteStr = new ByteArrayOutputStream();
			int byt = -1;
			while ((byt = in.read()) != -1) {
				byteStr.write(byt);
			}
			byte byteArr[] = byteStr.toByteArray();
			return defineClass(null, byteArr, 0, byteArr.length);
		} catch (final RuntimeException rex) {
			throw rex;
		} catch (final Exception ex) {
			ex.printStackTrace();
			throw new ClassNotFoundException(name);
		} finally {
			if (in != null) {
				try {
					in.close();
				} catch (final IOException ioe) {
					ioe.printStackTrace();
				}
			}
		}
	}
};
loader.loadClass("garbage").newInstance();

Bundle bundle = Activator.getDefault().getBundle();
bundle.loadClass(filename).newInstance();