java - why does JSTL tags displayed as question marks when I deploy my web application?

Question

I'm following the Netbeans E-Commerce tutorial which is based on Java EE technology and it took me two days to eliminate all the problems including database connection and understand the functionality of the web application, now I finally manage to run the entire web application which I downloaded from the Netbeans Tutorial. but there's a problem the JSTL tags displays ???? question marks, the code snippets below shows how it is implemented:

    <c:forEach var="category" items="${categories}">

    <c:choose>
        <c:when test="${category.name == selectedCategory.name}">
            <div class="categoryButton" id="selectedCategory">
                <span class="categoryText">
                    <fmt:message key="${category.name}"/>
                </span>
            </div>
        </c:when>
        <c:otherwise>
            <a href="<c:url value='category?${category.id}'/>" class="categoryButton">
                <span class="categoryText">
                    <fmt:message key="${category.name}"/>
                </span>
            </a>
        </c:otherwise>
    </c:choose>

</c:forEach>

and here's what it looks like when I run it on my browser, the server that this web app is running on is GLASSFISH:

In the image the underlined question marks are the JSTL tags, when I try to remove the tags the question marks doesn't appear but I can't remove the whole for loop.

Answer 1

これらのクエスチョンマークは

<fmt:message key="${category.name}"/>

がある場合は、 をキーとして使用しているが、リソース バンドルにキーが見つからない???Action???ことを意味します。fmt:messageActionAction