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主题：小妹有礼了请高手不吝指教

nimei [专家分：0] 发布于 2006-06-07 16:48:00

小妹自己写了一个水电费收费记录可是出现异常无奈只得求教这里的大哥大姐们知道
先说这是异常显示：
  java.lang.NumberFormatException: null
    at java.lang.Integer.parseInt(Integer.java:436)
    at java.lang.Integer.parseInt(Integer.java:518)
    at Scan1.doPost(Scan1.java:98)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:165)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:103)
    at com.caucho.server.http.FilterChainServlet.doFilter(FilterChainServlet.java:96)
    at com.caucho.server.http.Invocation.service(Invocation.java:315)
    at com.caucho.server.http.CacheInvocation.service(CacheInvocation.java:135)
    at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:253)
    at com.caucho.server.http.HttpRequest.handleConnection(HttpRequest.java:170)
    at com.caucho.server.TcpConnection.run(TcpConnection.java:139)
    at java.lang.Thread.run(Thread.java:534)

我知道是将String 转换int时出错可能出现在session转换中但就是不知道该如何处理

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回复列表（共10个回复）

沙发

nimei [专家分：0] 发布于 2006-06-07 16:51:00

这是我写的代码;
哎呀不能全发我就分段发送名字我就不写了。
import java.io.*;
import java.sql.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class WorkerList extends HttpServlet{
    static final private String content_type="text/html;charset=GB2312";
    String[] hot_water;
    String[] cool_water;
    String[] electric_quantity;
    String[] riqi;
    int firstnum=1;
    int count=0;
    public void init() throws ServletException{

    }
    public void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{
        doPost(request,response);
    }
    public void doPost(HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException{
        int i=0;

板凳

nimei [专家分：0] 发布于 2006-06-07 16:53:00

try{
            ResultSet rs=getWorks();
            while(rs.next()){
                count++;
            }
            setHot_water(count);
            setCool_water(count);
            setElectric_quantity(count);
            setRiqi(count);
            String hotWater[]=new String[count];
            hotWater=hot_water;
            String coolWater[]=new String[count];
            coolWater=cool_water;
            String electricQuantity[]=new String[count];
            electricQuantity=electric_quantity;
            String riqiCount[]=new String[count];
            riqiCount=riqi;
            response.setContentType(content_type);
            PrintWriter out=response.getWriter();

            out.println("<html>");
            out.println("<head>");
            out.println("<title>数据录入界面</title>");
            out.println("</head>");
            out.println("<body topmargin=5 marginheight=0 leftmargin=0 marginwidth=0 bgcolor=#80a0a0>");
            out.println("<center>");
            out.println("<font face='华文新魏' size=8>鸿源公司水电费统计表</font>");
            out.println("<hr size=5 color=#c0ff40><br>");
            out.println("<br>");
            out.println("<form action=http://localhost:8080/12/servlet/Scan1 method=post>");
            out.println("<table topmargin=0 border=1 bgcolor=#80a0a0 width=780>");
            out.println("<tr>");
            out.println("<td>用户名</td>");
            out.println("<td>楼房号</td>");
            out.println("<td>凉水量</td>");
            out.println("<td>热水量</td>");
            out.println("<td>用电量</td>");
            out.println("<td rowspan=3>");
            out.println("<p align=left>年</p>");
            out.println("<select name=year>");
            out.println("<option value=2006>2006</option>");
            out.println("<option value=2007>2007</option>");
            out.println("<option value=2008>2008</option>");

            out.println("</select>");
            out.println("<p align=left>月</p>");
            out.println("<select name=month>");
            out.println("<option value=1>01</option>");
            out.println("<option value=2>02</option>");
            out.println("<option value=3>03</option>");
            out.println("<option value=4>04</option>");
            out.println("<option value=5>05</option>");
            out.println("<option value=6>06</option>");
            out.println("<option value=7>07</option>");
            out.println("<option value=8>08</option>");
            out.println("<option value=9>09</option>");
            out.println("<option value=10>10</option>");
            out.println("<option value=11>11</option>");
            out.println("<option value=12>12</option>");
            out.println("</select>");
            out.println("</td>");
            out.println("</tr>");
            String number=String.valueOf(count);
            HttpSession session=request.getSession();
            session.setAttribute("number",number);
            rs.beforeFirst();
            while(rs.next()){
            String userName=rs.getString("用户名");
            String add=rs.getString("房间号");
            out.println("<tr>");
            out.println("<td align=left >"+userName+"</td>");
            out.println("<td align=left >"+add+"</td>");
            out.println("<td><input type=text name=cool_water["+i+"] ></td>");
            out.println("<td><input type=text name=hot_water["+i+"] ></td>");
            out.println("<td><input type=text name=electric_quantity["+i+"] ></td>");
            i++;

3 楼

nimei [专家分：0] 发布于 2006-06-07 16:54:00

}
            out.println("</tr></table></center><br>");
            out.println("<p align=center>");
            out.println("<input type=submit name=sub value=提交>");
            out.println("</p>");
            out.println("</form></body></html>");
    }catch(Exception e){
        e.printStackTrace();
        }
    }
    public ResultSet getWorks(){
        try{
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            Connection con=DriverManager.getConnection("jdbc:odbc:shuidian");
            Statement stm=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
            ResultSet rs=stm.executeQuery("select * from user");
            return rs;
        }catch(Exception e){
            e.printStackTrace();
        }
        return null;
    }
    public void setHot_water(int waterCount){
        if(firstnum==1){
            hot_water=new String[count];
            for(int a=0;a<count;a++){
                hot_water[a]="0";
            }
        }
        firstnum++;
    }
    public void setCool_water(int coolCount){
        if(firstnum==1){
            cool_water=new String[count];
            for(int a=0;a<count;a++){
                cool_water[a]="0";
            }
        }
        firstnum++;
    }

4 楼

nimei [专家分：0] 发布于 2006-06-07 16:54:00

public void setElectric_quantity(int ele_count){
        if(firstnum==1){
            electric_quantity=new String[count];
            for(int a=0;a<count;a++){
                electric_quantity[a]="0";
            }
        }
        firstnum++;
    }
    public void setRiqi(int riqinum){
        if(firstnum==1){
            riqi=new String[count];
            for(int a=0;a<count;a++){
                riqi[a]="0";
            }
        }
        firstnum++;
    }
    public void destroy(){}
}

5 楼

nimei [专家分：0] 发布于 2006-06-07 16:56:00

上面的是一个文件然后传入下面的文件
import java.sql.*;
import java.util.*;
import java.io.*;
import javax.servlet.http.*;
import javax.servlet.*;
public class Scan extends HttpServlet{
    static final private String content_type="text/html;charset=GB2312";
    Vector vector=new Vector();
    int num;
    public void init() throws ServletException{    }
    public void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{
        doPost(request,response);
    }
    public void doPost(HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException{
            response.setContentType(content_type);
            PrintWriter out=response.getWriter();
            out.println("<html>");
            out.println("<head>");
            out.println("<title>数据浏览界面</title>");
            out.println("</head>");
            out.println("<body topmargin=5 marginheight=0 leftmargin=0 marginwidth=0 bgcolor=#80a0a0>");
            out.println("<center>");
            out.println("<font face='华文新魏' size=8>鸿源公司水电费统计表</font>");
            out.println("<hr size=5 color=#c0ff40><br>");
            out.println("<br>");
            Vector info_vec=new Vector();


            int coolTotalQuantity=0;
            int hotTotalQuantity=0;
            int eleTotalQuantity=0;

            double hotPrice=3.00;
            double coolPrice=2.95;
            double elePrice=0.50;

            num=0;
            out.println("the dates you inputed are:</br>");
            out.println("<form action=http://localhost:8080/12/servlet/AddInformation method=post>");
            out.println("<table border=1><tr>");
            out.println("<td>用户名</td>");
            out.println("<td>房间号</td>");
            out.println("<td>凉水单价</td>");
            out.println("<td>凉水用量</td>");
            out.println("<td>凉水总费用</td>");
            out.println("<td>热水单价</td>");
            out.println("<td>热水用量</td>");
            out.println("<td>热水总费用</td>");
            out.println("<td>用电单价</td>");
            out.println("<td>用电量</td>");
            out.println("<td>用电总费用</td>");
            out.println("<td>年月份</td>");
            out.println("<td>总费用</td></tr>");
            int i=0;

6 楼

nimei [专家分：0] 发布于 2006-06-07 16:56:00

try{
                ResultSet rs=getList();
                while(rs.next()){
                    num++;
                }
                String[] true_value1=new String[num];
                String[] true_value2=new String[num];
                String[] true_value3=new String[num];
                String riqi1=request.getParameter("year");
                String riqi2=request.getParameter("month");
                String riqi=riqi1+"/"+riqi2;
                for(int j=0;j<num;j++){
                    true_value1[j]=request.getParameter("cool_water["+j+"]");
                    true_value2[j]=request.getParameter("hot_water["+j+"]");
                    true_value3[j]=request.getParameter("electric_quantity["+j+"]");

                }
                rs.beforeFirst();
                while(rs.next()){
                    out.println("<tr>");
                    String userName=rs.getString("用户名");
                    String address=rs.getString("房间号");
                        Vector vec=new Vector();
                        vec.addElement(userName);
                        vec.addElement(address);
                        vec.addElement(String.valueOf(coolPrice));
                        vec.addElement(true_value1[i]);
                        double coolWater_price=coolPrice * Double.parseDouble(true_value1[i]);
                        vec.addElement(String.valueOf(coolWater_price));
                        vec.addElement(String.valueOf(hotPrice));
                        vec.addElement(true_value2[i]);
                        double hotWater_price=hotPrice * Double.parseDouble(true_value2[i]);
                        vec.addElement(String.valueOf(hotWater_price));
                        vec.addElement(String.valueOf(elePrice));
                        vec.addElement(true_value3[i]);
                        double ele_price=elePrice * Double.parseDouble(true_value3[i]);
                        vec.addElement(String.valueOf(ele_price));
                        vec.addElement(riqi);
                        double totalPrice=coolWater_price+hotWater_price+ele_price;
                        vec.addElement(String.valueOf(totalPrice));
                        info_vec.addElement(vec);
                        i++;
                }
            }catch(Exception e){
                e.printStackTrace();
            }

7 楼

nimei [专家分：0] 发布于 2006-06-07 16:57:00

setvector(info_vec);
            for(int j=0;j<info_vec.size();j++){
               for(int k=0;k<13;k++){
                if(k==12){
                    out.println("<td>"+getValueAt(j,k)+"</td></tr>");
                }else{
                    out.println("<td>"+getValueAt(j,k)+"</td>");
                }
                      }

                coolTotalQuantity=coolTotalQuantity+Integer.parseInt(getValueAt(j,3).toString());
                hotTotalQuantity=hotTotalQuantity+Integer.parseInt(getValueAt(j,6).toString());
                eleTotalQuantity=eleTotalQuantity+Integer.parseInt(getValueAt(j,9).toString());
                out.println("<tr>");
            }
            out.println("</tr></table>");
            out.println("</tr></table>");

            HttpSession session=request.getSession();
            session.setAttribute("vector",vector);
            out.println("<p align=center>凉水总量："+coolTotalQuantity+"</p>");
            out.println("<p align=center>热水总量："+hotTotalQuantity+"</p>");
            out.println("<p align=center>用电总量："+eleTotalQuantity+"</p>");
            out.println("<p align=center>");
            out.println("<input type=submit value=confim>");
            out.println("<p>");
            out.println("</form>");
            out.println("</body></html>");
        }
        public Object getValueAt(int row,int column){
            if(! vector.isEmpty()){
                return ((Vector)vector.elementAt(row)).elementAt(column);
            }else{
                return null;
            }
        }
    public ResultSet getList(){
        try{
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            Connection con=DriverManager.getConnection("jdbc:odbc:shuidian");
            Statement stm=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
            ResultSet rs=stm.executeQuery("select * from user");
            return rs;
        }catch(Exception ex){
            ex.printStackTrace();
        }
        return null;
    }
    public void setvector(Vector v){
        vector=v;
    }
    public void destroy(){}
}

8 楼

nimei [专家分：0] 发布于 2006-06-07 16:59:00

关键的错误就出现在这一个里面了还望大哥大姐们带着雷锋的精神帮俺看看怎么处理
import java.io.*;
import java.sql.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class AddInformation extends HttpServlet{
    static final private String content_type="text/html;charset=GB2312";
    Connection con=null;
    Vector vector=new Vector();
    public void init() throws ServletException{}
    public void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{
        doPost(request,response);
    }
    public void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{
        response.setContentType(content_type);
        PrintWriter out=response.getWriter();
        HttpSession session=request.getSession();
        vector=(Vector)session.getAttribute("vector");
        out.println("<html>");
        out.println("<head><title>添加页面</title></head>");
        out.println("<body>");
        Vector ve=new Vector();
        ve=vector;
        String number=(String)session.getAttribute("number");
        int num=Integer.parseInt(number);


        int coolTotalQuantity=0;
        int hotTotalQuantity=0;
        int eleTotalQuantity=0;

        for(int i=0;i<ve.size();i++){

            String user=String.valueOf(getValueAt(i,0).toString());
            String addr=String.valueOf(getValueAt(i,1).toString());
            double coolWater_price=Double.parseDouble(getValueAt(i,2).toString());
            int coolWater_quantity=Integer.parseInt(getValueAt(i,3).toString());
            double coolWater_Tprice=Double.parseDouble(getValueAt(i,4).toString());
            double hotWater_price=Double.parseDouble(getValueAt(i,5).toString());
            int hotWater_quantity=Integer.parseInt(getValueAt(i,6).toString());
            double hotWater_Tprice=Double.parseDouble(getValueAt(i,7).toString());
            double ele_price=Double.parseDouble(getValueAt(i,8).toString());
            int ele_quantity=Integer.parseInt(getValueAt(i,9).toString());
            double ele_Tprice=Double.parseDouble(getValueAt(i,10).toString());
            String riqi=String.valueOf(getValueAt(i,11).toString());
            double totalPrice=Double.parseDouble(getValueAt(i,12).toString());
            coolTotalQuantity+=coolWater_quantity;
            hotTotalQuantity+=hotWater_quantity;
            eleTotalQuantity+=ele_quantity;
            addRecord(user,addr,coolWater_price,coolWater_quantity,coolWater_Tprice,hotWater_price,hotWater_quantity,hotWater_Tprice,ele_price,ele_quantity,ele_Tprice,riqi,totalPrice);


        }

9 楼

nimei [专家分：0] 发布于 2006-06-07 17:02:00

addTotalQuantity(coolTotalQuantity,hotTotalQuantity,eleTotalQuantity);
        out.println("<p align=center>sucess</p>");
    }
    public void addRecord(String user,String addr,double coolWater_price,int coolWater_quantity,double coolWater_Tprice,double hotWater_price,int hotWater_quantity,double hotWater_Tprice,double ele_price,int ele_quantity,double ele_Tprice,String riqi,double totalPrice){
        try{
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            Connection con=DriverManager.getConnection("jdbc:odbc:shuidian");
            Statement stm=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
            String sql="insert into information(用户名,房间号,凉水单价,凉水用量,凉水总费用,热水单价,热水用量,热水总费用,用电量,用电单价,用电总费用,年月份,总费用) values ('"+user+"','"+addr+"','"+coolWater_price+"','"+coolWater_quantity+"','"+coolWater_Tprice+"','"+hotWater_price+"','"+hotWater_quantity+"','"+hotWater_Tprice+"','"+ele_quantity+"','"+ele_price+"','"+ele_Tprice+"','"+riqi+"','"+totalPrice+"')";
            stm.executeUpdate(sql);
            stm.close();

        }catch(Exception e){
            System.out.println(e.getMessage());
            e.printStackTrace();
        }
    }
    public void addTotalQuantity(int coolTotalQuantity,int hotTotalQuantity,int eleTotalQuantity){
        try{
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            Connection con=DriverManager.getConnection("jdbc:odbc:shuidian");
            Statement stm2=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
            String sql2="insert into totalQuantity(凉水总量,热水总量,用电总量) values ('"+coolTotalQuantity+"','"+hotTotalQuantity+"','"+eleTotalQuantity+"')";
            stm2.executeUpdate(sql2);
            stm2.close();
        }catch(Exception e){
            System.out.println(e.getMessage());
            e.printStackTrace();
        }
    }
    public Object getValueAt(int row,int column){
        if(! vector.isEmpty()){
            return ((Vector)vector.elementAt(row)).elementAt(column);
        }else{
            return null;
        }
    }
    public void destroy(){}
}

10 楼

nimei [专家分：0] 发布于 2006-06-07 17:06:00

发完了。反正我估计错误就是出现在8楼的String number=(String)session.getAttribute("number");
int num=Integer.parseInt(number);
里面有什么好的解决方案吗？我曾经尝试过将后2个文件合并可还是出现那种该死的错误。小妹先谢过大家了 ~.~

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