java 如何比较JSTL中的参数
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How to compare parameters in JSTL
提问by Moham Qmaizer
I have list of ID's from a database and pass them in a request to a servlet, but i can't compare them to any number.
我有来自数据库的 ID 列表，并将它们在请求中传递给 servlet，但我无法将它们与任何数字进行比较。
I think maybe i have to convert them to integer type:
我想也许我必须将它们转换为整数类型：
<c:forEach items="${subjec.id}" var="x">
${x}
</c:forEach>
<c:forEach items="${listPage}" var = "list">
${list.id}
<c:choose>
<c:when test="${list.id} == 1">
</c:when>
</c:choose>
</c:forEach>
<c:if test="${subject1.id == 1}">
${subject1.id}
</c:if>
However, I cant test based on Integer format. Any suggetions for this case?
但是，我无法基于整数格式进行测试。对这种情况有什么建议吗？
回答by BalusC
<c:when test="${list.id} == 1">
This is wrong. You need to put the entireexpression inside ${}.
这是错误的。您需要将整个表达式放入${}.
If getId()returns a Number(integer, long, etc), then use the following:
如果getId()返回Number（整数、长整数等），则使用以下命令：
<c:when test="${list.id == 1}">
Or if it returns a String(which is unnatural by the way), then use the following:
或者，如果它返回 a String（顺便说一下，这是不自然的），则使用以下内容：
<c:when test="${list.id == '1'}">
Or if it returns a boolean(just as an example), then use the following:
或者，如果它返回一个boolean（仅作为示例），则使用以下内容：
<c:when test="${list.id}">
回答by Abhinab Kanrar
it should be <c:when test="${list.id == '1'}">
if you use <c:when test='${list.id == "1"}'>exception will be thrown
应该是<c:when test="${list.id == '1'}">
如果你使用<c:when test='${list.id == "1"}'>异常会被抛出
回答by krackmoe
try
尝试
<c:when test='${list.id == "1"}'>
