LINQ中ForEach方法的使用

LINQ中ForEach方法的使用。

1、实例一：使用ForEach获取列表中的某个字段值

/// <summary>
/// 使用ForEach获取列表中员工名称字段
/// </summary>
static void Main(string[] args)
{
    List<Emplayee> emplayeeList = GetEmplayeeList();  //获取员工信息列表
    string empNames = "";                             //员工名称字段
    emplayeeList.ForEach(a => empNames += a.EmplayeeName + ",");
    empNames = empNames.TrimEnd(',');
    Console.WriteLine(empNames);                     //输出：张三,李四,王五
}

2、实例二：使用ForEach将部门列表与员工列表关联 

/// <summary>
/// 使用ForEach将部门列表与员工列表关联
/// </summary>
public static void JoinDepartmentList()
{
    List<Department> departmentList = GetDepartmentList();   //获取部门信息列表
    List<Emplayee> emplayeeList = GetEmplayeeList();         //获取员工信息列表
    departmentList.ForEach(a => a.EmplayeeList = emplayeeList.Where(e => e.DepartmentId == a.DepartmentId).ToList());

    //使用ForEach输入结果
    departmentList.ForEach(a => Console.WriteLine(String.Format("{0}:员工数量：{1}", a.DepartmentName, a.EmplayeeList.Count)));
}

其它代码：

/// <summary>
/// 部门信息类
/// </summary>
public class Department
{
    /// <summary>
    /// 部门ID
    /// </summary>
    public int DepartmentId { get; set; }

    /// <summary>
    /// 部门名称
    /// </summary>
    public string DepartmentName { get; set; }

    /// <summary>
    /// 员工列表
    /// </summary>
    public List<Emplayee> EmplayeeList { get; set; }
}

/// <summary>
/// 员工信息类
/// </summary>
public class Emplayee
{
    /// <summary>
    /// 员工姓名
    /// </summary>
    public string EmplayeeName { get; set; }

    /// <summary>
    /// 部门ID
    /// </summary>
    public int DepartmentId { get; set; }
}

/// <summary>
/// 获取员工信息列表
/// </summary>
/// <returns></returns>
public static List<Emplayee> GetEmplayeeList()
{
    List<Emplayee> emplayeeList = new List<Emplayee>();
    Emplayee emplayee1 = new Emplayee() { EmplayeeName = "张三", DepartmentId = 1, };
    Emplayee emplayee2 = new Emplayee() { EmplayeeName = "李四", DepartmentId = 2, };
    Emplayee emplayee3 = new Emplayee() { EmplayeeName = "王五", DepartmentId = 2, };
    emplayeeList.Add(emplayee1);
    emplayeeList.Add(emplayee2);
    emplayeeList.Add(emplayee3);
    return emplayeeList;
}

/// <summary>
/// 获取部门信息列表
/// </summary>
/// <returns></returns>
public static List<Department> GetDepartmentList()
{
    List<Department> departmentList = new List<Department>();
    Department department1 = new Department() { DepartmentId = 1, DepartmentName = "研发部" };
    Department department2 = new Department() { DepartmentId = 2, DepartmentName = "人事部" };
    Department department3 = new Department() { DepartmentId = 3, DepartmentName = "财务部" };
    departmentList.Add(department1);
    departmentList.Add(department2);
    departmentList.Add(department3);
    return departmentList;
}