我有一个带有以下参数的Car对象:
private String model;
private BigDecimal price;
private Color color;
private BigDecimal milleage;
private List<String> components;
我创建了一个Car对象列表:
var cars = List.of(
Car.create("FORD", BigDecimal.valueOf(120000), Color.RED, BigDecimal.valueOf(150000),
List.of("AIR CONDITIONING", "VOICE SERVICE")),
Car.create("FORD", BigDecimal.valueOf(160000), Color.RED, BigDecimal.valueOf(150000),
List.of("AIR CONDITIONING", "VOICE SERVICE")),
Car.create("AUDI", BigDecimal.valueOf(200000), Color.BLACK, BigDecimal.valueOf(195000),
List.of("NAVIGATION", "AUTOMATIC GEARBOX")),
Car.create("FIAT", BigDecimal.valueOf(70000), Color.BLUE, BigDecimal.valueOf(85000),
List.of("AIR CONDITIONING", "MANUAL GEARBOX")));
现在我想创建一个
Map<String, List<Car>>
,其中字符串是组件列表的元素,List<Car>
是包含此组件的Car
对象的列表。我尝试了一些类似问题的解决方法,但真的不知道如何解决这个问题。
static Map<String, List<Car>> carsThatGotComponent(List<Car> cars) {
return cars.stream()
.flatMap(car -> car.getComponents()
.stream()
.map(component -> new AbstractMap.SimpleEntry<>(car, component)))
.collect(Collectors.groupingBy(
Map.Entry::getValue,
Collectors.mapping(Map.Entry::getKey, Map.Entry::getValue)));
}