java list分组 list里面分装的都是对象 按照对象的属性来分组

http://www.iteye.com/problems/86110

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List<Bill> list = billFacade.findBillByUserId(userInfo);
Map<String, Float> group = new HashMap<String, Float>();
String type = null;
Float moneyTotal = 0f;
for(Bill bill : list){
type = bill.getType();

moneyTotal = group.get(type);

if(moneyTotal == null){

moneyTotal = 0f;

}

group.put(type, moneyTotal + bill.getMoney());

}