jsp code compilation error

hai, iam doing online banking project.i created two database tables in mysql.Table1: user (username,password) Table2: myaccounts (accno,username,balance).

for funds transferring, i had written the following code.but it shows the following error.can you tell me where is the error and also what is the proper code for funds transfer.



<%@page import="java.sql.*"%>
<%
int acc1=Integer.parseInt(request.getParameter("no"));
int bal=Integer.parseInt(request.getParameter("amount"));
int acc2=Integer.parseInt(request.getParameter("to"));

try {
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/register";, "root", "root");
Statement st = con.createStatement();

ResultSet rs = st.executeQuery( "select balance from myaccounts where ano='"+acc1+"'");

int balance1=0;
while (rs.next()) {
balance1=rs.getInt("balance");
}
ResultSet rs1 = st.executeQuery( "select balance from myaccounts where ano='"+acc2+"'");

int balance2=0;
while (rs1.next()) {
balance2=rs1.getInt("balance");
}

int bal1=balance1-bal;
int bal2=balance2+bal;

st.addBatch("update myaccounts set balance="+bal1+" where ano='"+acc1+"'");
st.addBatch("update myaccounts set balance="+bal2+" where ano='"+acc2+"'");
st.executeBatch();
out.println("Transaction has been successfully done.");
}
catch(Exception e){}
%>





HTTP Status 500 -

--------------------------------------------------------------------------------

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: null
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:372)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)


root cause

java.lang.NumberFormatException: null
java.lang.Integer.parseInt(Integer.java:415)
java.lang.Integer.parseInt(Integer.java:497)
org.apache.jsp.xxxxxxxxxxxxxxx_jsp._jspService(xxxxxxxxxxxxxxx_jsp.java:62)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)


note The full stack trace of the root cause is available in the Apache Tomcat/5.0.30 logs.