Support_Resources.copyFile(resources, "JarIndex", "hyts_13.jar"); JarFile jarFile = new JarFile(resources.getAbsolutePath() + "/JarIndex/hyts_11.jar"); Manifest mf = jarFile.getManifest(); Attributes attrs = mf.getMainAttributes(); attrs.putValue("Class-Path", "file:/" + resPath + "/JarIndex/hyts_13.jar"); File mainJar = new File(resources.getAbsolutePath() + "/JarIndex/main.jar"); JarOutputStream jos = new JarOutputStream(new FileOutputStream(mainJar), mf); jos.flush(); jos.close(); assertTrue(mainJar.exists()); URL[] urls = new URL[1]; urls[0] = new URL("file:/" + resPath + "/JarIndex/main.jar"); ucl = URLClassLoader.newInstance(urls, null); assertNotNull(Class.forName("Main2", true, ucl)); } }