Question

我有一个类型为PARENT的数组列表，并且列表中有子类型，我们称它们为CHILD1和CHILD2。

当前，我的列表看起来像[CHILD1 x, CHILD2 y, CHILD1, a]，但我想要将CHILD1元素放在第一位，即IE [CHILD1 x, CHILD1 a, CHILD2, y]

我可以在流中应用按类型过滤器分组吗？

Answer 1

Assuming that the number of subtypes is not too large and that you are not dealing with further subtypes of the children, you can simply make a list of subtypes with the order you want and sort by the position in the list:

List<Class<? extends Parent>> order = Arrays.asList(Child1.class, Child2.class, Child3.class, ...);
Comparator<Parent> bySubtype = Comparator.comparing(p -> order.indexOf(p.getClass()));

list.sort(bySubtype);  // sort in place

List<Parent> sorted = list.stream()
                         .sorted(bySubtype)
                         .collect(Collectors.toList());   // sort into a new list with a stream

Java 8过滤以根据列表中的类型对数据进行排序？

1 个答案: