如何在我的选择框中列出日期格式为yyyy-mm-dd的月份值

Question

This is my code:

<form>
    <table>
        <tr>
            <td>Month</td>
            <td>
                <select name="">
                    <option value="">January</option>
                    <option value="">February</option>
                    <option value="">March</option>
                    <option value="">April</option>
                    <option value="">May</option>
                    <option value="">June</option>
                    <option value="">July</option>
                    <option value="">August</option>
                    <option value="">September</option>
                    <option value="">October</option>
                    <option value="">November</option>
                    <option value="">December</option>
                </select>
            </td>
        </tr>
        <tr>
            <td>Year</td>
            <td><input type="text" name="year"></td>
        </tr>
        <tr>
            <td><input type="submit" value="Submit"></td>
        </tr>
    </table>
</form>

I want to put the month values in the option value. Let say that 2013-07-16 is the date with the date format of yyyy-mm-dd in SimpleDateFormat. How can I put the value of July or "07" in my option value with this kind of format.

Answer 1

<fmt:format var="month" value="${theDate}" pattern="MM"/>
<select name="">
    <option value="01" ${month == "01" ? "selected='selected'" : ""}>January</option>
    <option value="02" ${month == "02" ? "selected='selected'" : ""}>February</option>
    ...
</select>

There is a lot of repetition, though, in this code, so you'd better prepare a List<SelectableMonth> in your controller, and iterate over this list:

 <select name="">
    <c:forEach var="month" items="${selectableMonths}">
        <option value="${month.number}" ${month.selected ? "selected='selected'" : ""}>${month.label}</option>
    </c:forEach>        
</select>

Answer 2

I haven't written any JSP in years but I think this should point you in the right direction:

<%@ taglib uri="http://java.sun.com/jstl/core"    prefix="c" %>
<%@ taglib uri="http://java.sun.com/jstl/core_rt" prefix="c-rt" %>

<%!
  String[] months = { "January","February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
%>

<form>
    <table>
        <tr>
            <td>Month</td>
            <td>
                <select name="">
                  <c-rt:forEach var="month" items="<%= months %>">
                      <option value="${i}">${months[i]}</option>
                  </c-rt:forEach>
                </select>
            </td>
        </tr>
        <tr>
            <td>Year</td>
            <td><input type="text" name="year"></td>
        </tr>
        <tr>
            <td><input type="submit" value="Submit"></td>
        </tr>
    </table>
</form>

Answer 3

Let say that 2013-07-16 is the date with the date format of yyyy-mm-dd in SimpleDateFormat. How can I put the value of July or "07" in my option value with this kind of format.

Your question is a little unclear, but it sounds like you're asking if you have a date value modelled by a String , and a SimpleDateFormat that matches the pattern of that value, how can you modify the format to output it in a new way? Is that what you're looking for?

If that is what you're asking, you'd need twwo more instances of SimpleDateFormat to model the new formats you want to use — one to model the month name and other for its numeric value. You could then use the parse(String source) method to turn your String into a Date & reformat it from there. If you want to take this approach, something like the below should work.

Be careful of throwing a ParseException if taking this approach though. You'd be better to start from a Date instead, if possible.

<%
    String today = "2013-07-16";
    SimpleDateFormat yearMonthDay = new SimpleDateFormat("yyyy-MM-dd");
    Date todaysDate = yearMonthDay.parse(today);

    String monthAsNumber = new SimpleDateFormat("MM").format(todaysDate);
    String monthAsFullName = new SimpleDateFormat("MMMMM").format(todaysDate);
%>

<select>
    <option value="<%= monthAsNumber %>"><%= monthAsFullName %></option>
</select> 

Also, it would be best practice to remove this type of Java code from the JSP altogether for testability, re-use etc — You should look into using JSTL functions, that will allow you to move the data parsing out into a separate class & then use a bean to render out the two values you need to display per date.