rs.next处抛出异常！

下面这段程序：
String data = "-";
while(rs.next()) {
%>
<tr>
<%
for(i=0;i<count;i++)
{
System.err.println（i）;

if(i == 5)
{
float temp = rs.getFloat(i+1);
data = Float.toString(db.SellPrice(temp));
}
else
{
data = rs.getString(i+1);
if(data==null)
data = "-";
}
System.err.println(data);
%>
<td><%=data%></td>
<%
}
}

下面出错提示，中间包含err.println的数出结果：
0

1000232

1

手术刀柄

2

3号-200MM

3

24

4

把

5

16.15

6

StandardWrapperValve[debugjsp]: Servlet.service() for servlet debugjsp threw exception

java.lang.NullPointerException

java.lang.NullPointerException

at oracle.jdbc.driver.ScrollableResultSet.getCachedDatumValueAt(ScrollableResultSet.java:1307)

at oracle.jdbc.driver.ScrollableResultSet.getOracleObject(ScrollableResultSet.java:398)

at oracle.jdbc.driver.ScrollableResultSet.getString(ScrollableResultSet.java:406)

at org.apache.jsp.main$jsp._jspService(main$jsp.java:167)

at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:107)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)

at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:202)

at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:382)