와일드카드란?The wildcard ? in Java is a special kind of type argument[1] that controls the type safety of the use of generic (parameterized) types. It can be used in variable declarations and instantiations as well as in method definitions, but not in the definition of a generic type.[  public static void peekBox(Box box){ System.out.println(box); }// 제네릭 메소드 정의public static void peekBox(Box box){ Sy..