Question

我正在处理员工的数组列表，并且需要按员工人数，活动员工数和非活动员工数按功能使用分组。我知道如何处理总数，但是当值在数组字符串中时（即一名员工与多个部门关联），如何按功能按组处理数组列表。

public class Employee {
    private String name;
    private List<String> department;
    private String status;
    public Employee(String name, List<String> department, String status) {
        this.setName(name);
        this.setDepartment(department);
        this.setStatus(status);
    }
    public String getName() {
        return name;
    }
    public List<String> getDepartment() {
        return department;
    }
    public void setName(String name) {
        this.name = name;
    }
    public void setDepartment(List<String> department) {
        this.department = department;
    }
    public String getStatus() {
        return status;
    }
    public void setStatus(String status) {
        this.status = status;
    }
}

ArrayList<Employee> listEmployee = new ArrayList<Employee>();

         List<String> listString1 = Arrays.asList("IT", "Sales");
         List<String> listString2 = Arrays.asList("Sales");
         List<String> listString3 = Arrays.asList("Sales");


         listEmployee.add(new Employee("Ravi", listString1, "active"));
         listEmployee.add(new Employee("Tom", listString2, "inactive"));
         listEmployee.add(new Employee("Kanna", listString3, "inactive"));

int count = 0;
for (Employee e : listEmployee) {
    count++;
}
System.out.println("Count of Employees" + count);

这是我试图获取员工人数的上述代码

int count = 0;
for (Employee e : listEmployee) {
    count++;
}
System.out.println("Count of Employees" + count);

请按部门分组帮助我处理数据

我期望以下输出：

Department total activeCount inactiveCount
IT         1     1           0
Sales      3     1           2

Answer 1

首先，我们需要创建一个类，其中包含每个部门的计数器。
类似于下面的预兆（为简洁起见，将实例变量设为public）。我们需要将此类的实例放入equals()

中，因此需要hashCode()和Map

public class DepartmentStats {
    public String name;
    public int total = 0;
    public int activeCount = 0;
    public int inactiveCount = 0;

    public DepartmentStats() {}
    public DepartmentStats(String name) {
        this.name = name;
    }

    /**
     * equality based on dept name
     */
    @Override
    public boolean equals(Object other) {
        return other instanceof DepartmentStats && 
               this.name.equals(((DepartmentStats) other).name);
    }

    /**
     * hash code based on dept name
     */
    @Override
    public int hashCode() {
        return name.hashCode();
    }
}

第二，我们将创建一个地图，该地图将使我们能够按部门对员工进行分组并保存累积计数器

Map<String, DepartmentStats> departmentStatsMap = new HashMap<>();

现在，直接遍历员工列表是一件简单的事情，对于每个项目，遍历部门列表，从地图上获取适当的条目并累积计数器（然后放回地图）：< / p>

for (Employee employee : listEmployee) {
    for (String departmentName : employee.getDepartment()) {
        DepartmentStats departmentStats = departmentStatsMap.get(departmentName);
        if (departmentStats == null) departmentStats = new DepartmentStats(departmentName);
        departmentStats.total++;
        if (employee.getStatus().equals("active")) departmentStats.activeCount++;
        if (employee.getStatus().equals("inactive")) departmentStats.inactiveCount++;
        departmentStatsMap.put(departmentName, departmentStats);
    }
}

我如何处理带有计数的ArrayList并按函数分组，值中包含字符串数组

1 个答案: