java - 使用子类的值过滤类的流

Question

我有一个父类Company，它有一个Employee对象列表。我需要创建一个 Parent 类的流，该类有一个带有上述电话号码的 Employee 。

Company cmp1 = new Company();
cmp1.setName("oracle");

Company cmp2 = new Company();
cmp1.setName("Google");

Employee emp1 = new Employee();
emp1.setName("David");
emp1.setPhone("900");
Employee emp2 = new Employee();
emp2.setName("George");
emp2.setPhone("800");
Employee emp4 = new Employee();
emp4.setName("BOB");
emp4.setPhone("300");
Employee emp5 = new Employee();
emp5.setName("taylor");
emp5.setPhone("900");

List<Employee> cmp1EmpList1 = new ArrayList<Employee>();
cmp1EmpList1.add(emp1);
cmp1EmpList1.add(emp2);
cmp1.setEmployees(cmp1EmpList1);

List<Employee> cmp1EmpList2 = new ArrayList<Employee>();
cmp1EmpList2.add(emp4);
cmp1EmpList2.add(emp5);

cmp2.setEmployees(cmp1EmpList2);

List<Company> companies = Arrays.asList(cmp1, cmp2);

为了检索流，我尝试添加以下代码

List<Company> companiesWithEmployeesphone800 = companies.stream()
    .filter(loc -> loc.getEmployees()
                    .stream()
                    .flatMap(locnew -> locnew.getPhone()
                                        .equalsIgnoreCase("800"))
            )
    .collect(Collectors.toList());

但收到了不兼容的类型。

Answer 1

使用anyMatch作为谓词而不是flatMap:

List<Company> companiesWithEmployeesphone800 =
    companies.stream()
            .filter(loc -> loc.getEmployees().stream()
                    .anyMatch(locnew -> locnew.getPhone().equalsIgnoreCase("800")))
            .collect(Collectors.toList());