List根據指定屬性排序（實現IComparer介面）

問題：

   有一個List<CourseList> testlist,類CourseList中有CourseId, CourseName,CourseStatus,TeacherName,LevelName,StudentNumber這五個屬性。現在想實現testlist的按CourseList類的各個屬性排序。

 

解決辦法：

 

定義各屬性的枚舉類型

public enum CompareType{    CourseId,    CourseName,    CourseStatus,    TeacherName,    LevelName,    StudentNumber}

 

實現IComparer介面

public class CourseListComparer:IComparer<CourseList>{       private CompareType _compareColumn;    public CompareType CompareColumn    {        get { return _compareColumn; }        set { _compareColumn = value; }    }    public CourseListComparer(CompareType t) {        this._compareColumn = t;    }    /// <summary>    /// compare by different property    /// </summary>    /// <param name="x">CourseList x</param>    /// <param name="y">CourseList y</param>    /// <returns>int </returns>    public int Compare(CourseList x,CourseList y) {               switch (this.CompareColumn) {            case CompareType.CourseId:                return x.CourseId.CompareTo(y.CourseId);            case CompareType.CourseName:                return x.CourseName.CompareTo(y.CourseName);            case CompareType.CourseStatus:                return x.CourseStatus.CompareTo(y.CourseStatus);            case CompareType.TeacherName:                return x.TeacherName.CompareTo(y.TeacherName);            case CompareType.LevelName:                return x.LevelName.CompareTo(y.LevelName);            case CompareType.StudentNumber:                return x.StudentNumber.CompareTo(y.StudentNumber);            default: return x.CourseId.CompareTo(y.CourseId);        }    }}

調用sort方法

CourseListComparer courselistComparer = new CourseListComparer(CompareType.CourseId);testList.Sort(courselistComparer);

 

原因：

        C#中的List<>有兩個Sort方法，一個是無參的，一個是帶IComparer參的。無參的方法是按預設的比較子進行排序，有參的就要自己定義一個實現IComparer介面。

       實現ICompare介面就需要實現Compare方法。Compare方法有兩個要比較的輸入，根據自己定義的比較規則，返回int值，0表示相等，1表示x>y,-1表示x<y.