关于list集合报错的问题

Question

ChangeOrderControl aChangeOrderControl = new ChangeOrderControl();
ChangeOrderModel aChangeOrderModel = (ChangeOrderModel)aChangeOrderControl.getModel(ID);
Map beans = new HashMap();
if(aChangeOrderModel!=null){

//获得子表信息
ChangeOrderBillControl aChangeOrderBillControl = new ChangeOrderBillControl();
String strSQL = "select * from t_moc_ChangeOrderBill where PID = '" + ID + "'";
ArrayList al = aChangeOrderBillControl.getItemBySQL(strSQL);

ArrayList list=new ArrayList();
for(int i=0;i<al.size();i++){
ChangeOrderBillModel m = (ChangeOrderBillModel)al.get(i);

Map map=new HashMap();
map.put("NODENAME",m.getNODENAME());
map.put("BGPRICE",PublicTools.format(m.getBGPRICE(),3));
map.put("BGNUMBER",m.getBGNUMBER());
map.put("BGMONEY",PublicTools.format(m.getBGMONEY(),3));

list.add(map);

}

beans.put("list",list);
beans.put("BSDW",aChangeOrderModel.getBSDW());
}

Answer 1

如果aChangeOrderModel为null，你这个if不进入，那么beans里面没有list和bsdw参数。
你页面上如果没有判断，就会出错。