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Illogical jsp error

开发者 https://www.devze.com 2023-01-20 21:17 出处:网络
I want to dispaly a result parameter which return from servlet to jsp after an event happen. so when i add new user for example a result parameterreturns with value that the user has been added succes

I want to dispaly a result parameter which return from servlet to jsp after an event happen. so when i add new user for example a result parameter returns with value that the user has been added successfully , and i want to display the result in jsp page. i make like this in jsp page

<%String result = String.valueOf(request.getAttribute("result"));%>
 <%if (result != null){%>
 <%= result%>
<%}%&开发者_开发问答gt;

THE PROBLEM is that every time i open the page for the first time result prints as null to the browser even i write if not null print result value, where is the problem ? can someone help/


String.valueOf(..) returns "null" (a String with length 4) if the argument is null. So your quick solution would be not to use String.valueOf(..) at all.

However, it is not advisable to use scriptlets and java code like that in your JSPs. Use JSTL and EL instead. Your code would look like this:

<c:if test="${result != null}">
    ${result}
</c:if>
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