ArrayList,List,Hashtable,Dictionary的应用

ArrayList list = new ArrayList();

list.Add(new Student("aaa", 20));
list.Add(new Student("bbb", 21));
list.Add(new Student("ccc", 22));

for (int i = 0; i < list.Count; i++)
{
    Student stu = list[i] as Student;
    Console.WriteLine(string.Format("Name:{0}   Age:{1}", stu.Name, stu.Age));
}
foreach (Object obj in list)
{
    Student stu = obj as Student;
    Console.WriteLine(string.Format("Name:{0}   Age:{1}", stu.Name, stu.Age));
}

List<Student> list = new List<Student>();

list.Add(new Student("aaa", 20));
list.Add(new Student("bbb", 21));
list.Add(new Student("ccc", 22));

for (int i = 0; i < list.Count; i++)
{
    Console.WriteLine(string.Format("Name:{0}   Age:{1}", list[i].Name, list[i].Age));
}
foreach (Student stu in list)
{
    Console.WriteLine(string.Format("Name:{0}   Age:{1}", stu.Name, stu.Age));
}

Hashtable hs = new Hashtable();

hs.Add("aaa", 20);
hs.Add("bbb", 21);
hs.Add("ccc", 22);

foreach (DictionaryEntry de in hs)
{
    Console.WriteLine(string.Format("Key:{0}    Value:{1}",de.Key,de.Value));
}

Dictionary<string, int> dict = new Dictionary<string, int>();

dict.Add("aaa", 20);
dict.Add("bbb", 21);
dict.Add("ccc", 22);

foreach (KeyValuePair<string, int> kvp in dict)
{
    Console.WriteLine(string.Format("Key:{0}    Value:{1}", kvp.Key, kvp.Value));
}