使用“List”可以防止强制转换错误。它对于避免运行时强制转换错误非常有用。

例子:

在这里(使用ArrayList)，您可以编译这段代码，但稍后会看到一个执行错误。

    // Create a new ArrayList


    System.Collections.ArrayList mixedList = new System.Collections.ArrayList();


    // Add some numbers to the list
    mixedList.Add(7);
    mixedList.Add(21);


    // Add some strings to the list
    mixedList.Add("Hello");
    mixedList.Add("This is going to be a problem");




    System.Collections.ArrayList intList = new System.Collections.ArrayList();
    System.Collections.ArrayList strList = new System.Collections.ArrayList();


    foreach (object obj in mixedList)
    {
        if (obj.GetType().Equals(typeof(int)))
        {
            intList.Add(obj);
        }
        else if (obj.GetType().Equals(typeof(string)))
        {
            strList.Add(obj);
        }
        else
        {
            // error.
        }
    }

是的，差不多。List<T>是泛型类。它支持存储特定类型的值，而不强制转换为对象(当T是ArrayList情况下的值类型时，这会引起装箱/拆箱开销)。ArrayList仅存储对象引用。作为一个泛型集合，List<T>实现了泛型IEnumerable<T>接口，可以很容易地在LINQ中使用(不需要任何Cast或OfType调用)。

ArrayList属于c#没有泛型的时代。不赞成使用List<T>。你不应该在以。net >= 2.0为目标的新代码中使用ArrayList，除非你必须与使用它的旧API进行交互。

To me its all about knowing your data. If I am continuing to expand my code on the basis of efficiency, I would have to choose the List option as a way of deciphering of my data w/o the unnecessary step of always wondering about types, especially 'Custom Types'. If the machine understands the difference and can determine on it's on what type of data I'm actually dealing with then why should I get in the way and waste time going thru the gyrations of 'IF THEN ELSE' determinations? My philosophy is to let the machine work for me instead of me working on the machine? Knowing the unique differences of different object code commands goes a long way in making your code as efficient.

汤姆•约翰逊 (一项…一个出口)

再加上以上几点。在64位操作系统中使用ArrayList占用的内存是32位操作系统的2倍。同时，泛型列表list <T>占用的内存比ArrayList少得多。

例如，如果我们在32位中使用一个19MB的数组列表，那么在64位中它将占用39MB。但是如果你有一个32位的8MB的通用列表list <int>，它在64位只需要8.1MB，这与ArrayList相比相差了481%。

来源:数组列表与通用列表的基本类型和64位

ArrayList是不同类型数据的集合，而List<>是其自身依赖的相似类型数据的集合。

要添加的另一个区别是线程同步。

ArrayList provides some thread-safety through the Synchronized property, which returns a thread-safe wrapper around the collection. The wrapper works by locking the entire collection on every add or remove operation. Therefore, each thread that is attempting to access the collection must wait for its turn to take the one lock. This is not scalable and can cause significant performance degradation for large collections. List<T> does not provide any thread synchronization; user code must provide all synchronization when items are added or removed on multiple threads concurrently.

更多信息在这里线程同步在.Net框架