java8 分组计数 Collectors.groupingBy Collectors.counting

                            java8 分组计数 Collectors.groupingBy Collectors.counting

//分组计数
Map<String, Long> colorNum = appleList.stream().collect(Collectors.groupingBy(Apple::getColor, Collectors.counting()));
colorNum.forEach((k, v) -> System.out.println("分组计数:" + k + " " + v));
Map<String, Long> placeNum = appleList.stream().collect(Collectors.groupingBy(Apple::getPlaceOfOrigin, Collectors.counting()));
placeNum.forEach((k, v) -> System.out.println("分组计数：" + k + " " + v));

分组计数:红 3
分组计数:黄 1
分组计数:绿 2
分组计数：山东 3
分组计数：辽宁 2
分组计数：河北 1