编写高质量代码改善C#程序——使用泛型集合代替非泛型集合(建议20)

  ArrayList al=new ArrayList();
      al.Add(0);
      al.Add(1);
      al.Add("mike");
      foreach (var item in al)
      {
        Console.WriteLine(item);
      }

 ArrayList al=new ArrayList();
      al.Add(0);
      al.Add(1);
      al.Add("mike");
      int t = 0;
      foreach (int item in al)
      {
        t += item;
      }

var intArr = new int[] {0, 1, 2, 3};
ArrayList al=new ArrayList(intArr);

public virtual void InsertRange(int index, ICollection c)
{
  if (c == null)
  {
    throw new ArgumentNullException("c", Environment.GetResourceString("ArgumentNull_Collection"));
  }
  if ((index < 0) || (index > this._size))
  {
    throw new ArgumentOutOfRangeException("index", Environment.GetResourceString("ArgumentOutOfRange_Index"));
  }
  int count = c.Count;
  if (count > 0)
  {
    this.EnsureCapacity(this._size + count);
    if (index < this._size)
    {
      Array.Copy(this._items, index, this._items, index + count, this._size - index);
    }
    object[] array = new object[count];
    c.CopyTo(array, 0);
    array.CopyTo(this._items, index);
    this._size += count;
    this._version++;
  }
}

List<int> intList = new List<int>();
      intList.Add(1);
      intList.Add(2);
      //intList.Add("mike");
      foreach (var item in intList)
      {
        Console.WriteLine(item);
      }

 static void Main(string[] args)
    {
      Console.WriteLine("开始测试ArrayList:");
      TestBegin();
      TestArrayList();
      TestEnd();
      Console.WriteLine("开始测试List<T>:");
      TestBegin();
      TestGenericList();
      TestEnd();
    }
    static int collectionCount = 0;
    static Stopwatch watch = null;
    static int testCount = 10000000;
    static void TestBegin()
    {
      GC.Collect();  //强制对所有代码进行即时垃圾回收
      GC.WaitForPendingFinalizers(); //挂起线程，执行终结器队列中的终结器（即析构方法）
      GC.Collect();  //再次对所有代码进行垃圾回收，主要包括从终结器队列中出来的对象
      collectionCount = GC.CollectionCount(0);  //返回在0代码中执行的垃圾回收次数
      watch = new Stopwatch();
      watch.Start();
    }

    static void TestEnd()
    {
      watch.Stop();
      Console.WriteLine("耗时：" + watch.ElapsedMilliseconds.ToString());
      Console.WriteLine("垃圾回收次数：" + (GC.CollectionCount(0) - collectionCount));
    }

    static void TestArrayList()
    {
      ArrayList al = new ArrayList();
      int temp = 0;
      for (int i = 0; i < testCount; i++)
      {
        al.Add(i);
        temp = (int)al[i];
      }
      al = null;
    }

    static void TestGenericList()
    {
      List<int> listT = new List<int>();
      int temp = 0;
      for (int i = 0; i < testCount; i++)
      {
        listT.Add(i);
        temp = listT[i];
      }
      listT = null;
    }