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将对象转换为泛型列表

.net c#

6

Amit Sharma · 技术社区 · 16 年前

a type T or List<T>

namespace Generic_Collection_Code
{
    class Program
    {
        public static string DumpObj(object obj)
        {
            string sTemp = String.Empty;

            List<int> ints = obj as List<int>;
            if (ints != null)
            {
                foreach (int i in ints)
                    sTemp += i.ToString() + ",";
                sTemp.Trim(',');
            }
            else 
            {
                List<string> strings = obj as List<string>;
                if (strings != null)
                {
                    foreach (string s in strings)
                        sTemp += s + ",";
                    sTemp.Trim(',');
                }
                else
                {
                    sTemp += obj.ToString();
                }
            }
            return sTemp;
        }
        static void Main(string[] args)
        {
            List<int> listInts = new List<int>();
            listInts.Add(1);
            listInts.Add(2);
            listInts.Add(3);

            Console.WriteLine("Object1: {0}", DumpObj(listInts));
            int i = 90;

            Console.WriteLine("Object2 {0}", DumpObj(i));


            List<string> listStrings = new List<string>();
            listStrings.Add("1");
            listStrings.Add("2");
            listStrings.Add("3");

            Console.WriteLine("Object3: {0}", DumpObj(listStrings));
            Console.ReadKey();
        }
    }
}

    public static string DumpObj<T>(object obj)
    {
        string sTemp = String.Empty;

        List<T> list = obj as List<T>;
        if (list != null)
        {
            foreach (T i in list)
                sTemp += i.ToString() + ",";
            sTemp.Trim(',');
        }
        return sTemp;
    }

5 回复 | 直到 13 年前

1

11

Charlie Flowers 16 年前

List<T> genericList = object as List<T>;

if(genericList != null)
{
   // Do the loop
}

“as”关键字验证“object”实际上是一个“List<T>如果是这样,您将得到一个列表<T>如果没有,则返回null。

2

9

Dave 16 年前

您遇到的编译错误是什么?如果T在上下文中被声明为泛型类型参数,那么我在该语句中看到的唯一编译时问题就是关键字的使用 object

IEnumerable enumerable = obj as IEnumerable;

if (enumerable != null)
{
    foreach (object item in enumerable)
    {
        sTemp += item.ToString();
    }
}

StringBuilder

3

4

Brijesh Mishra 16 年前

你不能这么做

List<T> genericList = (List<T>)object

List<T> genericList = (List<T>)obj

其中obj是对象

4

0

MarcE 16 年前

把“as”和“is”结合起来怎么样?

if (object is List<T>)
{ 
  List<T> genericlist = object as List<T>;
 // loop list
}
else if (object is T)
{
 // do something else
}

5

0

Khanh Hua 13 年前

private static void DataSourcePropertyChanged(DependencyObject sender,     
        DependencyPropertyChangedEventArgs args) {
        BarChart _ = sender as BarChart;

        if (args.Property.Equals(BarChart.DataSourceProperty)) {
            System.Collections.IList data = (System.Collections.IList)args.NewValue;
            if (data == null) return;

            foreach (object __ in data) {
                IChartDataItem item = __ as IChartDataItem;
                BarChartItem bar = new BarChartItem() {
                    Label = item.Label,
                    Value = item.Value
                };
                _._visualCollection.Add(bar);

                if (_.MaxData < item.Value)
                    _.MaxData = item.Value;
            }

            if (_.Orientation == Orientation.Horizontal)
                _.Ratio = _.Width / _.MaxData;
        }
    }