对ArrayList中的自定义类型进行搜索

小灰灰 2021-04-23 15:12 399阅读 0赞

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();        
     }