日期:2014-05-18  浏览次数:20793 次

list与 null问题 大家帮下忙
<%
  if   (zhiXiaoPosList!=null){%>    
  <td   width= "24% "   colspan= "13 "   align= "left ">     <img   src= "../images/dot1.gif "> <a   href= " <%=request.getContextPath()%> /query/QueryZhiXiaoPos.jsp "   target= "under "> <%=zhiXiaoPosseatnm%> 代销1 </a>   </td>
    <%}   else   if(nongHangList!=null   ){
                    out.print( "888 "+nongHangList);
                for   (int   i   =   0;   i   <   nongHangList.size();   i++)   {
                      java.util.HashMap   map   =   null;
        map     =   (HashMap)nongHangList.get(   i);
                      String   seatno   =   map.get( "seatno ").toString();
                      String   seatnm   =   map.get( "seatnm ").toString();
      out.print(seatnm+ "*** ");
  %>
<td   width= "24% "   colspan= "13 "   align= "left ">       <img   src= "../images/dot1.gif "> <a   href= " <%=request.getContextPath()%> /query/QueryDaiXiaoFund.jsp "   target= "under "> <%=seatnm%> 代销 </a>     </td>  
  <%
    }
  }else{   %>
  <td   width= "24% "   colspan= "13 "   align= "left ">         </td>
 
  <%
  }
  %>


zhiXiaoPosList   明是空,nongHangList有值     为什么不显示 <td   width= "24% "   colspan= "13 "   align= "left ">       <img   src= "../images/dot1.gif "> <a   href= " <%=request.getContextPath()%> /query/QueryDaiXiaoFund.jsp "   target= "under "> <%=seatnm%> 代销代销代销 </a>     </td>
而显示
  <td   width= "24% "   colspan= "13 "   align= "left ">     <img   src= "../images/dot2.gif "> <a   href= " <%=request.getContextPath()%> /query/QueryZhiXiaoPos.jsp "   target= "under "> <%=zhiXiaoPosseatnm%> 代销1 </a>   </td>


------解决方案--------------------
list虽然不空,可是里面没值
------解决方案--------------------
if (zhiXiaoPosList!=null)

改成if(zhiXiaoPosList != null && zhiXiaoPosList.size()> 0)

试试
------解决方案--------------------
同意楼上的,我想这就是引用类型的问题

比如ArrayList list1 = null;这时候无疑为空
而ArrayList list2 = new ArrayList();
这时候list2已经不为空了,只不过list2.size() == 0而已

不知道说的准不准确