JSP and checkbox values

[KKLU]

Hello. Need some help. From the code below, JSP should print "True" only if the combination of A and C is submitted. All other false. It does not work though (even my teacher was lost ).

Excuse me, I'm new to this.

Thanks

HTML

<form method="get" action="index.jsp">
Question:<br>
a) Answer A <input type="checkbox" name="question" value="a"><br>
b) Answer B <input type="checkbox" name="question" value="b"><br>
c) Answer C <input type="checkbox" name="question" value="c"><br>
<input type="submit">
</form>

JSP

<%
                    if (request.getParameter("question").equals("a") & request.getParameter("question").equals("c")) {
                        out.print("True");
                    } else {
                        out.print("False");
                    }
%>

also tried

<%!            
String[] question;
%>
        <%
            question = request.getParameterValues("question");
            if (question[0] == "a" & question[1] == "c") {
                out.print("True");
            } else {
                out.print("False");
            }
         %>

[Fou-Lu]

Its been too long since I've used JSP, but I'm quite sure ops are the same. & is a bit operator, not a logical operator, and in typical java it should throw a compilation error since you cannot cast from int to boolean. Change those from & to &&.
Oh and use .equals. Strings are immutable, so while "a" == "a", "a" != new String("a"). Using .equals will always compare the value instead.

[KKLU]

Thanks. This works -- finally prints True.

<%!            
        String[] question;
        %>
        <%
            question = request.getParameterValues("question");
            if (question[0].equals("a") && question[1].equals("c")) {
                out.print("True");
            } else {
                out.print("False");
            
            }
          %>

So, I guess the reason this does not work

if (request.getParameter("question").equals("a") && request.getParameter("question").equals("c")) {
                        out.print("True");
                    } else {
                        out.print("False");
                    }

is because "question" has more than one value, hence needs to be added to a String and then compared?

[Fou-Lu]

Sting should always be compared with equals or equalsIgnoreCase, otherwise it compares the object values themselves.

For the retrieval, yeah that would be because its an array for checkbox, but I'm afraid I don't know exactly what's in it since JSP is different than how PHP handles checkboxes. I'm used to using JCheckBox within Java itself, but that is entirely different than how its handled from the request of JSP.