ArrayList的使用方法【转载】
转载了一篇关于《ArrayList的使用方法》的文章，讲解得非常清楚，可以很好地解释下面的问题：
（1） If interacting with collections from multiple threads, you must make the collection thread safe.
SAMPLE CODE:
ArrayList myAr = new ArrayList();
// Creates a synchronized wrapper around the ArrayList.
ArrayList mySyncedAr = ArrayList.Synchronized(myAr);
// To use collection from thread:
ArrayList myCollection = new ArrayList();
lock(myCollection.SyncRoot);
foreach ( Object item in myCollection )
{ // do work here }
Please note the following remarks from MSDN:
To guarantee the thread safety of the ArrayList, all operations must be done through this synchronized wrapper.
Enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads could still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.
（2）Initialize collection sizes at startup to speed up node creation.
ArrayList myAL = new ArrayList(); // Without initializing collection sizes
ArrayList myAL = new ArrayList(1000); // With initializing collection sizes
You can get more detailed information from the above article, ArrayList的使用方法.