Java8 对其中包含自定义 Object 的自定义对象进行排序

Question

我有一个员工 Object，部门 Object。我需要按员工 Object 字段排序，然后再按部门字段排序。 数据如下所示。

公共 static 列表 getEmployeeData() {

    Department account = new Department("Account", 75);
    Department hr = new Department("HR", 50);
    Department ops = new Department("OP", 25);
    Department tech = new Department("Tech", 150);

    List<Employee> employeeList = Arrays.asList(new Employee("David", 32, "Matara", account),
    new Employee("Brayan", 25, "Galle", hr), new Employee("JoAnne", 45, "Negombo", ops),
    new Employee("Jake", 65, "Galle", hr), new Employee("Brent", 55, "Matara", hr),
    new Employee("Allice", 23, "Matara", ops), new Employee("Austin", 30, "Negombo", tech),
    new Employee("Gerry", 29, "Matara", tech), new Employee("Scote", 20, "Negombo", ops),
    new Employee("Branden", 32, "Matara", account), new Employee("Iflias", 31, "Galle", hr));

    return employeeList;
    
}

我想按 Employee::name, Employee::Age, Department::DepartmentName 排序，如何排序？

Answer 1

这应该会导致预期的结果：

List<Employee> employees = getEmployeeData()
                .stream()
                .sorted(Comparator
                        .comparing(Employee::getName)
                        .thenComparing(Employee::getAge)
                        .thenComparing(e -> e.getDepartment().getName()))
                .collect(Collectors.toList());