code: public static File toFile(Object obj, File defaultValue) {
  	if (obj instanceof File) return (File) obj;
  	String str = Caster.toString(obj, null);
  	if (str == null) return defaultValue;
  	return FileUtil.toFile(str);
      }
docs: convert a object to a File
  
  @param obj
  @param defaultValue
  @return File