Check null values in Hashtable using java

Below is the code which shows the way to implement Hashtable in Java.

Also it shows the way to check the NULL values in Hashtable & exclude them while processing.

<%

        String qry_Relations = "SELECT * FROM RELATIONS WHERE ID<> 0 ORDER BY relationname";
       
        ResultSet rs_Relations = mdb.runQuery(qry_Relations);

        Hashtable<String, String> ht = new Hashtable<String, String>();

        while (rs_Relations.next()) {

            ht.put(rs_Relations.getString("id"), rs_Relations.getString("relationship"));
        }



        String keyvalue = "";

        String relationname = "";

        String relationcode = "";


%>
<table>

<tr>

 <td class="normal">


<select name="relation" id="relation" onChange="validate();" >


           <option value="0">SELECT  </option>


<%
   
//ITERATING THOUGH THE HASH TABLE


        for (int j = 1; j <= 10; j++) {

            //Checking for NULL values in hashtable. Get the values which are not NULL


            if(ht.get(String.valueOf(j)) != null)

        {

        keyvalue = ht.get(String.valueOf(j)).toString();
           
            
   
            if (keyvalue.equals(relationname)) {

%>
                <option value="<%=keyvalue%>" selected><%=keyvalue%>  </option>
   

<%
            } else {
   
%>
                <option value="<%=keyvalue%>" ><%=keyvalue%>  </option>
<%
                    }
                       
        }//if
                       
              }
          }

    %>           
        </select>


</td>

</tr>

</table>