LINQ中ForEach方法的使用

旧城等待， 2021-09-11 00:22 632阅读 0赞

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;
    }