对ArrayList中的自定义类型进行搜索

一般情况下我只需要使用ArrayList.Contains（）方法就可以判断某个元素是否存在，但如果ArrayList中的为自定义的类就需要自己实现，如下面例子：

如我们有一个类：

public class Employee
{
     public int EmployeeID
     {
            get;set;
     }

     public string EmployeeName
     {
           get;set;
     }

     public DateTime BirthDate
     {
           get; set;
     }

}

我们要实现对ArrayList中存储的Employee 进行查找。先定义两个枚举：

public enum MemType
{
    IntegerType = 1, StringType = 2, DateTimeType = 3, BooleanType = 4
};

public enum CmpOperator
{
    GreaterThan = 1, LessThan = 2, EqualTo = 3
}

下面是具体实现：

public static int Search(ArrayList objArr, string valueToSearch, string FieldName, MemType memType, CmpOperator comOp)
{
    if (memType == MemType.StringType || memType == MemType.BooleanType)
    {
        comOp = CmpOperator.EqualTo;
    }

    for (int i = 0; i < objArr.Count; i++)
    {
        Type t = objArr[0].GetType();
        System.Reflection.FieldInfo[] arrInner = t.GetFields();
        System.Reflection.PropertyInfo PI = t.GetProperty(FieldName);
        string str = PI.GetValue(objArr[i], null).ToString();
        switch (memType)
        {
            case MemType.BooleanType:
                if (Convert.ToBoolean(str) == Convert.ToBoolean(valueToSearch))
                {
                    return i;
                }
                break;
            case MemType.DateTimeType:
                switch (comOp)
                {
                    case CmpOperator.EqualTo:
                        if (Convert.ToDateTime(str).CompareTo(Convert.ToDateTime(valueToSearch)) == 0)
                        {
                            return i;
                        }
                        break;
                    case CmpOperator.GreaterThan:
                        if (Convert.ToDateTime(str).CompareTo(Convert.ToDateTime(valueToSearch)) > 0)
                        {
                            return i;
                        }
                        break;
                    case CmpOperator.LessThan:
                        if (Convert.ToDateTime(str).CompareTo(Convert.ToDateTime(valueToSearch)) < 0)
                        {
                            return i;
                        }
                        break;
                }
                break;
            case MemType.IntegerType:
                switch (comOp)
                {
                    case CmpOperator.EqualTo:
                        if (Convert.ToInt32(str) == Convert.ToInt32(valueToSearch))
                        {
                            return i;
                        }
                        break;
                    case CmpOperator.GreaterThan:
                        if (Convert.ToInt32(str) > Convert.ToInt32(valueToSearch))
                        {
                            return i;
                        }
                        break;
                    case CmpOperator.LessThan:
                        if (Convert.ToInt32(str) < Convert.ToInt32(valueToSearch))
                        {
                            return i;
                        }
                        break;
                }
                break;
            case MemType.StringType:
                if (str.Contains(valueToSearch))
                {
                    return i;
                }
                break;
        }
    }

    return -1;
}

测试代码如下：

static void Main(string[] args)
 {
     ArrayList al = new ArrayList();
     Employee emp1 = new Employee();
     emp1.EmployeeID = 2;
     emp1.EmployeeName = "cary";           
     emp1.BirthDate = new DateTime(1982, 4, 1);

     Employee emp2 = new Employee();
     emp2.EmployeeID = 3;
     emp2.EmployeeName = "james";           
     emp2.BirthDate = new DateTime(1983, 4, 1);

     al.Add(emp1);
     al.Add(emp2);

     int searIndex = Search(al, "3", "EmployeeID", MemType.IntegerType, CmpOperator.EqualTo);
     Console.WriteLine(searIndex);
     Console.ReadLine();        
 }