我无法使用StreamAPI的forEach打印地图

Question

我要打印部门名称和在每个部门工作的员工人数！

为什么每个流都无法正常工作？

ArrayList<Employee> list = EmployeeRepository.myList;

public Double getTotalSalary(){

    return list.stream().map(e -> e.getSalary()).reduce(0.0,(s1,s2) -> s1+s2);
}

public void departmentNamesAndEmployeeCount(){
    list.stream().collect(Collectors.groupingBy(Employee::getDepartment,Collectors.counting())).forEach(hm -> system.out::println); /// Compilation Error on this Line.

}

Answer 1

您是否在寻找：

.forEach((k, v) -> System.out.println(k + " " + v));