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Servlets

Getting a value from a checkbox

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posted 20 years ago

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I can't seem to retrieve a value from a checkbox. It is either checked or unchecked, a boolean. So how do I extract its value when it reaches the servlet?

<INPUT type="checkbox" value="guessorall" checked>

then once the form is submitted and sent to the servlet I do this...

String guessall = req.getParameter("guessorall");

It always returns null.

Bear Bibeault

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posted 20 years ago

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You need to set the name attribute of the checkbox. The name will become the request parameter, and if checked, its value will be the value of the value attribute. if unchecked, no request parameter will be created for it.

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Bear Bibeault

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posted 20 years ago

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For example

This will result, if checked, in a request parameter named 'xyz' whose value is the string 'true' (easily converted to a boolean). If unchecked, no 'xyz' parameter will be present.

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Kiran Sonaje

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posted 20 years ago

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Hi,
This code may help u
All the best

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
public class HttpRequestDemoServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<HTML>");
out.println("<HEAD>");
out.println("<TITLE>Obtaining Multi-Value Parameters</TITLE>");
out.println("</HEAD>");
out.println("<BODY>");
out.println("<BR>");
out.println("<BR>Select your favorite music:");
out.println("<BR><FORM METHOD=POST>");
out.println("<BR><INPUT TYPE=CHECKBOX " +
"NAME=favoriteMusic VALUE=Rock>Rock");
out.println("<BR><INPUT TYPE=CHECKBOX " +
"NAME=favoriteMusic VALUE=Jazz>Jazz");
out.println("<BR><INPUT TYPE=CHECKBOX " +
"NAME=favoriteMusic VALUE=Classical>Classical");
out.println("<BR><INPUT TYPE=CHECKBOX " +
"NAME=favoriteMusic VALUE=Country>Country");
out.println("<BR><INPUT TYPE=SUBMIT VALUE=Submit>");
out.println("</FORM>");
out.println("</BODY>");
out.println("</HTML>");
}
public void doPost(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
String[] values = request.getParameterValues("favoriteMusic");
response.setContentType("text/html");
PrintWriter out = response.getWriter();
if (values != null ) {
int length = values.length;
out.println("You have selected: ");
for (int i=0; i<length; i++) {
out.println("<BR>" + values[i]);
}
}
}
}

M Burke

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Posts: 434

posted 20 years ago

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yes, that helps. Thanks

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