Getting Checked checkboxes value and printing array elements to string instead of hashcode

Question

I have a JSP that gets a ResultSet object from a database, then it shows the values of the database in a table with checkboxes ready for selection, the only thing im having problems is getting those checked box values so that I can send them to my servlet then to another page showing a table of the selected items.

I've check everything that I can and I still cant find the answer.

Here's what i got: JSP for viewing data:

<%
                ResultSet results = (ResultSet)request.getAttribute("results");
                int countme=0;
                int numb=1;

        while (results.next()) {
                        ++countme;
                        numb=countme;

                    %>

        <tr>
                            <td><input type ="checkbox" id="cb_<%=(numb)%>"
                                       class="cbgroup"
                                       value="<%out.println(results.getString("ANI_TITLE"));%>"
                                       name="cbg" 
                                       />
                            </td>
            <td><%=results.getString("ANI_TITLE") %></td>
            <td><%=results.getString("ANI_STUDIO") %></td>
                            <td><%=results.getString("ANI_EPI") %></td>
        </tr>   
    <%  }

    %>

Then, once checked, you click the button that goes to this Servlet part:

else if (btn.equals("Continue")){
        token="delcont";
        String[] vals1=request.getParameterValues("cbg");
        }

        request.setAttribute("vals1", vals1);
        request.setAttribute("token", token);

        RequestDispatcher dispatch = request.getRequestDispatcher("deletechecked.jsp");
        dispatch.forward(request, response);


            }

and then the servlet sends it to this JSP for viewing the checked values in a table:

<h2>Are you sure to delete these?</h2>
    <table border="1" align="center">
    <tr>
        <th>Anime Title</th>
        <%--<th>Anime Studio</th>
                    <th>No. of Episodes</th>--%>
    </tr>
    <%
                String[] values = request.getParameterValues("cbg");
                String holder="";
                for(int i=0;i < values.length;i++){


                %>
                <tr><td><%=values%></td></tr>
                <% 
                    }
            %>

This code outputs a Hashcode of the array. We dont want that.

Hope you can help me. Thanks.

UPDATE: I got it working, but it prints the hashcode instead of the string. *Updated the Code above. It prints [Ljava.lang.String;@29cfc19f] as the array element.

Here, we have no idea how you send your request for the client to the serveltsm where the exception occurs exactly, .... did you check the request content ? — AxelH, Dec 02 '16 at 13:12
@AlexH i send the request via `
` and with this button redirecting it to the servlet `` The request content should be in vals1, but i checked it and it has "null" in it even when you check something. — Xenos29, Dec 02 '16 at 13:18
You should know that in HTML, the value of a checkbox is only present if it is checked, if not there is nothing. Check this http://www.w3schools.com/tags/tryit.asp?filename=tryhtml_input_checked — AxelH, Dec 02 '16 at 13:20
Well, I do know that. But it still doesn't get the value of the checked box. There must be a problem in `"name="cbg" />` that doesnt allow it to get the value from the table record. Or in the `String[] vals1=request.getParameterValues("cbg");` part, where it places the values to an array. — Xenos29, Dec 02 '16 at 13:25
Update your question, add the resulting from the client. Check if the values are correct. — AxelH, Dec 02 '16 at 13:29
I haven't coded the table yet, but it show be something like this `<% String[] values; values=request.getParameterValues("vals1"); for(int i=0;i < values.length;i++){ %> <%=values%> <% } %>` Also,now it produces a [Ljava.lang.String;@57eec887 when i simply print out what vals1 after the passed value goes to the servlet by changing this: `value="<%=results.getString("ANI_TITLE")%>"` in to a out.println — Xenos29, Dec 02 '16 at 13:32
_I haven't coded the table yet_ You used a table to put your database result ... you need to debug it. But you are not trying enough so I will let you find the solution. `NullPointerException` are verbose. Debug this and you will find your problem. — AxelH, Dec 02 '16 at 13:37
@AxelH Update, I got the values from the servlet after doing what I said in the last comment. BUT im still not able to get those values from the servlet to the View JSP, I think I need to do something about the `request.setAttributes` parts. — Xenos29, Dec 02 '16 at 13:49
You should use [jstl](http://stackoverflow.com/questions/3177733/how-to-avoid-java-code-in-jsp-files?rq=1) instead, much more readable. — AxelH, Dec 02 '16 at 13:59

score 1 · Accepted Answer · 2016-12-02T15:14:55.050

1

Problem is you have set attribute as:

request.setAttribute("vals1", vals1);

But you are trying to get using getParameterValues() and not getAttribute():

values=request.getParameterValues("vals1");

Use instead:

values=(String[])request.getAttribute("vals1");

OR simply:

values=request.getParameterValues("cbg");

You are simply printing array and not string:

<tr><td><%=values%></td></tr>

To print each selected values use index:

<tr><td><%=values[i]%></td></tr> <!-- note `[i]` -->

edited Dec 02 '16 at 15:14

answered Dec 02 '16 at 14:29

How stupid i am not to see that. Thanks for the answer. – Xenos29 Dec 02 '16 at 15:18

score 0 · Answer 2 · edited Jun 20 '20 at 09:12

0

Probably, you've got NullPointerException because when checkbox checked it's value is "on" (not a true) and when it's not the value is null (not a false)

edited Jun 20 '20 at 09:12

Community

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answered Dec 02 '16 at 12:55

Андрей Миронов

67
5

Getting Checked checkboxes value and printing array elements to string instead of hashcode

2 Answers2