java 合并list的方法

1.
    List reduce = list.stream()
            .map(x -> x.getChildren())
            .reduce(new ArrayList<>(), (all, item) -> {
                all.addAll(item);
                return all;
            });
    System.out.println(reduce);

2.
List collect = list.stream()
                             .map(Employee::getChildren)
                             .flatMap(Collection::stream)
                             .distinct().collect(Collectors.toList());
----------------------------

List childrens1 = new ArrayList<>();
for (long i =0;i<10;i++){
    childrens1.add(new Children(i,"x".concat(i+"")));
}
List childrens2 = new ArrayList<>();
for (long i =100;i<110;i++){
    childrens2.add(new Children(i,"x".concat(i+"")));
}
Employee mazi = new Employee("麻子", 90, 989.2);
mazi.setChildren(childrens1);
Employee lisi = new Employee("李四", 10, 1000.1);
lisi.setChildren(childrens2);
List list = Arrays.asList(mazi,lisi);