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Editorial Team
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Asked: 2026-05-14T01:30:12+00:00

i am new in JSP,i have some problem with the following code : <%@

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i am new in JSP,i have some problem with the following code :

    <%@ page contentType="text/html;charset=Big5" %>
<html>
    <head>
    <title></title>
    </head>
    <body>
        <form method="post" action="InsertStudent.jsp">
    <input type="text" size="20" name="txtName" />
    <input type="text" size="20" name="txtDob" />
    <input type="text" size="20" name="txtProStudied" />
    <input type="submit" name="B1" value="Submit" />     
        </form>

<% 
  if (request.getParameter("txtName") !="" && request.getParameter("txtDob") != "" && request.getParameter("txtProStudied") != "" ) {
              out.println("...bypass the if....statement");               
  }
%>

    </body>
</html>

If run this code, the out.println will fire even the 3 input box have value or not..

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1 Answer

  1. Editorial Team

    Because request.getParameter returns a string, you cannot use the != operator. You must use the equal function. The return value of request.getParameter might also be null. You need to check for that as well.

    if (request.getParameter("txtName") != null && !"".equals(request.getParameter("txtName")) 
 && request.getParameter("txtDob") != null && !"".equals(request.getParameter("txtDob")) 
 && request.getParameter("txtProStudied") != null && !"".equals(request.getParameter("txtProStudied"))) {
    out.println("...bypass the if....statement");               
}

    It would be ideal to define a function to test if the return value is either an empty string or null to reduce the code.

    public boolean isEmpty(String s)
{
    return (null == s || "".equals(s.trim()))
}
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