Java 8 Lambda-两个列表的交集

Question

我试图intersection根据某些条件并执行一些步骤来找到两个列表。在学习阶段找不到方法:)

Double totalAmount = 0.00d;
Double discount = 0.00d;


List<OrderLineEntry> orderLineEntryList = orderEntry.getOrderReleases().stream()
    .flatMap(orderReleaseEntry -> orderReleaseEntry.getOrderLines().stream())
    .filter(orderLineEntry -> orderLineEntry.getStatus().equals("PP") || orderLineEntry.getStatus().equals("PD"))
    .collect(Collectors.toList());

for (OrderLineEntry orderLineEntry : orderLineEntryList) {
    for (SplitLineEntry splitLineEntry : splitReleaseEntry.getLineEntries()) {
        if (splitLineEntry.getOrderLineId().equals(orderLineEntry.getId()) && splitLineEntry.getStatusCode() != "PX") {
            totalAmount += orderLineEntry.getFinalAmount();
            couponDiscount += orderLineEntry.getCouponDiscount() == null ? 0.00d : orderLineEntry.getCouponDiscount();
        }
    }
}

如您所见，逻辑很简单

根据某个过滤器从订单中获取所有项目，list并与另一个过滤器相交list并做一些事情。

Answer 1

最简单的方法是这样的：

List<T> intersect = list1.stream()
                         .filter(list2::contains)
                         .collect(Collectors.toList());