求助 数据库操作

Question

   servlet:
    public void updatemotherboard(HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException
 {
  RequestDispatcher rd=null;
  motherboard mbdao=new motherboard();
  String type=request.getParameter("type");
  if(!type.equals("domodify"))
  {
  int id=trans.strToint(request.getParameter("id"));
  motherboardjb mbjavabean=mbdao.queryList(id);
  request.setAttribute("result", mbjavabean);
  rd=request.getRequestDispatcher("../admin/updatemotherboard.jsp");
  rd.forward(request,response);   
  }
  else 
  {
  motherboardjb mhjavabean=new motherboardjb();
  mhjavabean.setMotherBoard_Name(trans.toChinese(request.getParameter("motherboardname")));
  mhjavabean.setInt_MotherBoard_Place(trans.strToint(request.getParameter("motherboardplace")));
  boolean =mbdao.operateMotherBoard("modify",mhjavabean);
  if()
  {
System.out.print("<script>alert('修改成功！')</script>");
response.sendRedirect("../admin/showmotherboard.jsp");
  }
  else
  {
  System.out.print("<script>alert(''修改失败！)</script>");
  response.sendRedirect("../admin/updatemotherboard.jsp");  
  }
  }
 }    页面：
    <form name="form1" action="servlet/MboardServlet" method="post">
 <input type="hidden" name="type" value="domodify">    
 <input type="hidden" name="action" value="modify">
 
<TABLE cellSpacing=0 cellPadding=2 width="95%" align=center border=0>
  <TR>
    <TD align=right>id:</TD>
    <TD style="COLOR: #880000"><input type="text" name="id" value="<%=result.getInt_MotherBoard_ID()%>"/></TD></TR>
  <TR>
  <TR>
    <TD align=right>版块名称:</TD>
    <TD style="COLOR: #880000"><input type="text" name="motherboardname" value="<%=result.getMotherBoard_Name()%>"/></TD></TR>
  <TR>
    <TD align=right>板块位置:</TD>
    <TD style="COLOR: #880000"><input type="text" name="motherboardplace" value="<%=result.getInt_MotherBoard_Place()%>"/></TD></TR>
  <TR align="center">
    <TD align="right"><input type="submit" name="submit" value="修改"/></TD>
    <TD align="left" style="COLOR: #880000"><input type="reset" name="reset" value="重设" /></TD></TR>
  <TR>
    <TD align=right>免费模板网：</TD>
    <TD style="COLOR: #880000"><a href="http://www.865171.cn">www.865171.cn</a></TD></TR></TABLE>
    </form>错误提示:严重: Servlet.service() for servlet MboardServlet threw exception
java.lang.NullPointerException
at com.servlet.MboardServlet.updatemotherboard(MboardServlet.java:120)
at com.servlet.MboardServlet.doPost(MboardServlet.java:44)
at com.servlet.MboardServlet.doGet(MboardServlet.java:19)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:228)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:216)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:634)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:445)
at java.lang.Thread.run(Thread.java:619)      是怎么回事？
  

Answer 1

19行出现问题了 
.MboardServlet.doGet(MboardServlet.java:19)

Answer 2

RequestDispatcher rd=null;
个人感觉 这一行代码出错了 你看看你的文件 19行哪里错了

Answer 3

mhjavabean.setMotherBoard_Name(trans.toChinese(request.getParameter("motherboardname")));
mhjavabean.setInt_MotherBoard_Place(trans.strToint(request.getParameter("motherboardplace")));
这两句有有一句或两句都没值，下次贴代码的时候加亮，还有行数也贴上要不这种没注释的代码看的很费劲