Getting values from id attribute in a servlet

In a html form I have wrritten this,<input type="text" id="demo">,Now if I use the method request.getAttribute("id") in the servlet I get a null value.Why is that?
How can I use "id" attribute declared in a html form ,in a servlet.Or is it the case that only getparameter will work with name attribute

id values are not used for form submissions, that's what the name attribute is for.

and you have to use request.getParameter("name"), not request.getAttribute("id") .

i have used the following in <input name="demo1" id="demo1" type="text">,now request.getParameter("demo1") fetches null!!

Is this input field inside the form that you're submitting?

Yes,I used the input field in side the form...Here is the entire form..I used id attributes inside test and Dept. Date field.

<form name="f1" method="post" action="BookingServlet">
<table>
<tr>
<td>
Source:</td>
<td>
<select name="src">
   <option value="???" style="color: gray;">from</option>
                    <option value='IXA'>Agartala </option>
                  <option value='AMD'>Ahmedabad </option>
                  <option value='IXU'>Aurangabad </option>
                  <option value='IXB'>Bagdogra </option>
                  <option value='BLR'>Bangalore </option>
                  <option value='BHO'>Bhopal </option>
                  <option value='MAA'>Chennai </option>
                  <option value='CJB'>Coimbatore </option>
                  <option value='CMB'>Colombo </option>
                  <option value='DEL'>Delhi </option>
                  <option value='GOI'>Goa </option>
                  <option value='GAU'>Guwahati </option>
                  <option value='HYD'>Hyderabad </option>
                  <option value='IDR'>Indore </option>
                  <option value='JAI'>Jaipur </option>
                  <option value='IXJ'>Jammu </option>
                  <option value='KTM'>Kathmandu </option>
                  <option value='COK'>Kochi </option>
                  <option value='CCU'>Kolkata </option>
                  <option value='IXM'>Madurai </option>
                  <option value='IXE'>Mangalore </option>
                  <option value='BOM'>Mumbai </option>
                  <option value='NAG'>Nagpur </option>
                  <option value='PNQ'>Pune </option>
                  <option value='RJA'>Rajahmundry </option>
                  <option value='SXR'>Srinagar </option>
				  <option value='STV'>Surat </option>
                  	<option value='TIR'>Tirupati </option>
				  	<option value='TRZ'>Trichy</option>
                 	<option value='TRV'>Trivandrum </option> 
			 		<option value='TCR'>Tuticorin</option>  
                  	<option value='VNS'>Varanasi </option>
                  	<option value='VGA'>Vijayawada </option>
                  	<option value='VTZ'>Vizag </option>
                  	</select></td></tr>
<tr><td>
Destination:</td>
<td>
<select name="desti">
<option value="???" style="color: gray;">to</option>
<option value='IXA'>Agartala </option>
<option value='AMD'>Ahmedabad </option>
<option value='IXU'>Aurangabad </option>
<option value='IXB'>Bagdogra </option>
<option value='BLR'>Bangalore </option>
<option value='BHO'>Bhopal </option>
<option value='MAA'>Chennai </option>
<option value='CJB'>Coimbatore </option>
<option value='CMB'>Colombo </option>
<option value='DEL'>Delhi </option>
<option value='GOI'>Goa </option>
<option value='GAU'>Guwahati </option>
<option value='HYD'>Hyderabad </option>
<option value='IDR'>Indore </option>
<option value='JAI'>Jaipur </option>
<option value='IXJ'>Jammu </option>
<option value='KTM'>Kathmandu </option>
<option value='COK'>Kochi </option>
<option value='CCU'>Kolkata </option>
<option value='IXM'>Madurai </option>
<option value='IXE'>Mangalore </option>
<option value='BOM'>Mumbai </option>
<option value='NAG'>Nagpur </option>
<option value='PNQ'>Pune </option>
<option value='RJA'>Rajahmundry </option>
<option value='SXR'>Srinagar </option>
 <option value='STV'>Surat </option>
<option value='TIR'>Tirupati </option>
<option value='TRZ'>Trichy</option>
<option value='TRV'>Trivandrum </option> 
<option value='TCR'>Tuticorin</option>  
<option value='VNS'>Varanasi </option>
<option value='VGA'>Vijayawada </option>
<option value='VTZ'>Vizag </option>
</select></td></tr>
<tr><td>Depart Date:</td><td><input name="demo1" id="demo1" type="text" size="25" style=" width : 102px;"><a href="javascript:NewCal('demo1','ddmmyyyy')"><img src="cal.gif" width="16" height="16" border="0" alt="Pick a date"></a>
</td></tr>
<tr><td>test</td><td><input type="text" id="test" name="test"></td></tr>
<tr><td>
  <select name="ADULT" >
                  <option value="1" selected="selected">1 Adult</option>
                  <option value="2">2 Adults</option>
                  <option value="3">3 Adults</option>
                  <option value="4">4 Adults</option>
                  <option value="5">5 Adults</option>
                  <option value="6">6 Adults</option>
                  <option value="7">7 Adults</option>
                  <option value="8">8 Adults</option>
                  <option value="9">9 Adults</option>
                </select>

</td>
<td>
<select name="CHILD" style=" width : 105px;">
                  <option value="0" selected="selected">0 Children</option>
                  <option value="1">1 Child</option>
                  <option value="2">2 Children</option>
                  <option value="3">3 Children</option>
                  <option value="4">4 Children</option>
                </select>

</td>
<td>
<select name="INFANT">
                  <option value="0" selected="selected">0 Infants</option>
                  <option value="1">1 Infant</option>
                  <option value="2">2 Infants</option>
                  <option value="3">3 Infants</option>
                  <option value="4">4 Infants</option>
                </select>
</td>
</tr>