如何从main访问嵌套类中的方法 - C#

时间:2013-05-30 10:32:32

标签: c# list nested-class

这是我第一个问题的编辑: 所以我再次检查了作业。 所有代码都在工作,因为我的教授希望它能够工作,但只有我之前提出的问题是我的问题。 - 如何直接从列表中执行方法ShowGrade(当然是这样):list [1] .ShowGrade(0)而不使用list [1] .s.ShowGrade(0)?? 我会把我所有的代码放在这里。 Main中的两个控制台线是他想要的(以及他想要的),我对作业的约束是: 1.嵌套课程课程学生课程(课程一名学生)。 2.除了默认构造函数之外,根本没有构造函数。 3. ShowGrade方法不在Course类中。 4.没有操作员。 (点)在ShowGrade中,只有[] 5.方法Q1中只有一个查询。

所以我的代码是:

场。 CS:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace HW_1
{
    public class Course 
    {
        private delegate int Del(Course c);

        internal string courseName { get; set; }

        public  class Student
        {
            internal string stuName { get; set; }
            internal List<int> gradesList { get; set; }

            //internal int ShowGrade(int index)
            //{
            //    return gradesList[index];
            //}
        }

        internal Student s = new Student();

        public override string ToString()
        {
            string gr = null;
            foreach (var g in s.gradesList)
                gr += g + " ";
            return string.Format("{0, -6} {1, -14} {2, -10}", courseName, s.stuName, gr);
        }

    }
}

Program.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace HW_1
{
    class Program
    {
        private delegate bool Del(Course c);

        static void Main(string[] args)
        {
            List<Course> list = new List<Course>
            { 
                new Course {courseName = "C#", s = new Course.Student {stuName = "Jojo", gradesList = new List<int>(){10, 20, 100}}},
                new Course {courseName = "C", s = new Course.Student {stuName = "Bambi", gradesList = new List<int>(){99}}},
                new Course {courseName = "Java", s = new Course.Student {stuName = "Bambi", gradesList = new List<int>(){}}}

            };

            Console.WriteLine("List of courses:");
            Print(list);

            Console.WriteLine("");
            Console.WriteLine("");
            Console.WriteLine("Press P / p for students who passed in average 60 and those who didn't.");
            Console.WriteLine("");
            Console.WriteLine("Press # for C# courses and others.");
            Console.WriteLine("");
            Console.WriteLine("Press any other key for courses with student who have at least one grade of 100 and all oter courses.");

            char ch = (char)Console.Read();
            Del d = ((ch == 'P' || ch == 'p') ? (Del)(c => c.s.gradesList.Count > 0 && c.s.gradesList.Average() >= 60) : ((ch == '#') ? (Del)(c => c.courseName == "C#") : (Del)(c => c.s.gradesList.Contains(100))));

            var x = Q1 <IGrouping<bool, Course>>(list, d);
            Print(x);

            Console.WriteLine("");
            //Console.WriteLine(list[1].ShowGrade(0));
            //Console.WriteLine(list[2].ShowGrade(3));

        }

        static IEnumerable<T> Q1<T>(IEnumerable<Course> list, Del d)
        {
            var query =
                from c in list
                orderby d(c)
                group c by d(c) into g
                select g;

            return (IEnumerable<T>)query;
        }

        static void Print(IEnumerable<IGrouping<bool, Course>> list)
        {
            Console.WriteLine();
            Console.WriteLine();
            Console.WriteLine("Q1 Results:");
            foreach (var g in list)
            {
                Console.WriteLine();
                Console.WriteLine(g.Key);
                Console.WriteLine("---------------");
                foreach (var c in g)
                    Console.WriteLine(c);
            }
        }

        static void Print<T>(IEnumerable<T> list)
        {
            foreach (var l in list)
                Console.WriteLine(l);
        }



    }
}

两个Console.writeline的输出必须是:

list[1].ShowGrade(0)
99
list[2].ShowGrade(3)

4 个答案:

答案 0 :(得分:1)

您有一个课程列表,其中的学生公开为s

Console.Writeline(list[1].s.ShowGrade(0));

因此,您需要访问s的{​​{1}}字段。不过,我建议您使用属性而不是公共字段:

list[x]

我实际上建议您将class Course { internal string c_name {get; set;} public Student Student { get; private set; } public Course() { this.Student = new Student(); } } 创建为非内部类。内部类应该只在本地使用。

Student

如果您想将class Student { internal s_name {get; set;} internal List<int> gradesList {get; set;} } 作为内部类,则必须使其Student 才能在public类之外使用它。< / p>

答案 1 :(得分:1)

list[n]会返回一个Course,其中有一个Student属性(一个课程可以有一个学生?),您可以从中显示成绩。

您的Student课程需要此方法:

public int ShowGrade(int index)
{
   return gradesList[index];
}

然后你可以打电话:

list[n1].s.ShowGrade(n2);

答案 2 :(得分:0)

您的代码肯定需要修改,因为存在问题,即

new Course ("C#", s.s_name = "Bob", s.gradesList = new List<int>(){100, 99, 85})

将无法编译,似乎您对传递构造函数参数&amp; object initialization

  

我不能使用构造函数

您只能在某种程度上使用对象初始化,例如,给定c_name是公开的,您可以这样做:

var course = new Course()
{
    c_name = "C#"
}

但是,你做不到:

var course = new Course()
{
    s.gradeList = ...
}

您只需手动设置此

即可
var course = new Course()
{
    c_name = "C#"
};
course.s.gradeList = new List<int>() { ... }

要回答你的问题,我会在这里使用一些封装,并在你的ShowGrade类中公开一个Course方法,它会给你你想要的代码,即

<击>
Console.Writeline(list[1].ShowGrade(0));

在内部,Course只会将呼叫委托给学生实例,例如

public int ShowGrade(int grade)
{
    return s.ShowGrade(grade);
}

<击>

刚才意识到你说你无法将ShowGrade添加到Course类,在这种情况下你只需要从Student即<{1}}获取Course属性/ p>

 list[0].s.ShowGrade(0);

便士只是放弃了这个,你需要拥有如下代码:

list[0].ShowGrade(0);

但无法修改Course类 - 唯一的选择是使用扩展方法,例如

public static class CourseExt
{
    public static int ShowGrade(this Course course, int grade)
    {
        return course.s.ShowGrade(grade);
    }
}
...
Console.WriteLine(list[0].ShowGrade(0));

答案 3 :(得分:0)

以下是您要求的代码:

class Course
{
    internal string CourseName { get; set; }
    public Student s { get; set; }

    public class Student
    {
        internal string StudentName { get; set; }
        internal IEnumerable<int> GradesList { get; set; }

        public int ShowGrade(int index)
        {
            if (GradesList == null)
                throw new NullReferenceException();
            return GradesList.ElementAt<int>(index);
        }
    }
}


class Program
{
    static void Main(string[] args)
    {
        List<Course> list = new List<Course>()
    {
        new Course () { CourseName = "C#", 
            s =  new Course.Student() { StudentName = "Bob", 
                                                                            GradesList = new List<int>() { 100, 99, 85 }}},  
        new Course () { CourseName = "Java", 
            s =  new Course.Student() { StudentName = "Bobi", 
                                                                            GradesList = new List<int>(){ 99, 90, 88 }}},
        new Course (){ CourseName = "C", 
            s = new Course.Student() { StudentName = "Roni", 
                                                                            GradesList = new List<int>()}},
        new Course (){ CourseName = "SQL", 
            s = new Course.Student() { StudentName = "Sean", 
                                                                            GradesList = new List<int>(){ 75, 62, 55 }}}
    };
        Console.WriteLine(list[0].s.ShowGrade(1));

        Console.ReadKey();
    }
}