java - 在 ArrayList 中查找重复值

Question

我是编程新手...

我有

List<DataProvider> dataProviders = new ArrayList<DataProvider>();

预期的输出是

[DataProvider [date=2017-04-05 00:24:47.0, pendingtickets=1, closedtickets=0, createdtickets=1], DataProvider [date=2017-04-04 01:34:58.0, pendingtickets=1, closedtickets=0, createdtickets=1], DataProvider [date=2017-04-04 16:48:34.0, pendingtickets=1, closedtickets=0, createdtickets=1], DataProvider [date=2017-04-05 16:49:54.0, pendingtickets=1, closedtickets=0, createdtickets=1]]

我想得到一个没有重复的 date 的列表，所有重复的列表值应该加起来..

Answer 1

如果我明白你想要什么，你可以做这样的事情:

Map<Date, DataProvider> res = new HashMap<Date, DataProvider>();
for (DataProvider dp : dataProviders) {
    if (!res.containsKey(dp.getDate())) {
        res.put(dp.getDate(), dp);
    }

    else{ 
        res.get(dp.getDate()).setPendingtickets(res.get(dp.getDate()).getPendingtickets() + dp.getPendingtickets());
        res.get(dp.getDate()).setClosedtickets(res.get(dp.getDate()).getClosedtickets() + dp.getClosedtickets());
        res.get(dp.getDate()).setCreatedtickets(res.get(dp.getDate()).getCreatedtickets());
    }
}
List<DataProvider> result = new ArrayList<DataProvider>(res.values());