The load3DS method takes 2 parameters, a string with the 3ds file path and a scale, you are not passing a path as String but a inputStram turned as String
your new code should be:
Object3D[] miss=Loader.load3DS (getFile, 2);
public String getFile (String File) {
return File;
}
the error mesage is clear enough: ERROR: Couldn't read file from InputStream