Hashtable简单范例代码

 
 

class Student 
{
        public Student(string name, int age) 
        {
            this .name = name;
            this .age = age;
        }
        private string name;
        public string Name
        {
            get
            {
                return name;
            }
            set
            {
                name = value ;
            }
        }
        private int age;
        public int Age
         {
            get 
            {
                return age;
            }
            set 
            {
                age = value ;
            }
        }
    }

    class Program
    {
        static void Main( string[] args)
         {
            //仍然使用Student的类来实现, Hashtable键值对形式: key/value,相当于字典,能根据学生的姓名快速的找到对象
            Student xyy = new Student( "小月月" , 14);
            Student fj = new Student( "凤姐" , 18);
            Student fr = new Student( "芙蓉姐姐" , 19);
            Student xl = new Student( "犀利哥" , 20);
            Hashtable student = new Hashtable();
            student.Add( "小月月" , xyy);
            student.Add( "凤姐" , fj);
            student.Add( "芙蓉姐姐" , fr);
            student.Add( "犀利哥" , xl);

            //student.Add("犀利哥",xl);         //错误:  字典中的关键字key是不允许重复的，所以不能再添加犀利哥

            //移除：  因为没有索引,所以没有RemoveAt()
            student.Remove( "小月月" );      //根据key来移除
            student.Clear();
            student.ContainsKey( "凤姐" ) ;  //判断是不是含有这个键

            //遍历:  因为字典没有索引,所以不能使用for来遍历,只能使用foreach

            //按key遍历经常用
            foreach (object key in student.Keys) 
            {
                Student stu = student[key] as Student;
                Console .WriteLine(key);
                Console .WriteLine(stu.Age);
            }

            //按value遍历
            foreach (object value in student.Values)
            {
                Student stu = value as Student;
                if (stu != null )
                {
                    Console .WriteLine(stu.Age);
                }
            }

            //如果不按key,也不按value遍历,对字典遍历就是对字典的键值对进行遍历
            foreach (DictionaryEntry de in student)
            {
                Console .WriteLine(de.Key);
                Student s = de.Value as Student;    //因为得到的是object类型, 所以还需要转换才可以使用
                Console .WriteLine(s.Age);
            }

            Student s2 = student["小月月" ] as Student ;  //通过姓名找到该对象 获取其他的属性
            if (s2 != null )
            {
                Console .WriteLine(s2.Age);
            }
            Console .Read();
        }
    }