C#心得与经验(二)
本周学到很多C#关于Interface, Array的知识,在这里简单复习一下几个易混的地方,重在理解。
一、Interface
使用as来避免多态时没有接口的Exception:
Document [] folder = new Document[5]; for (int i = 0; i < 5; i++) { if (i % 2 == 0) { folder[i] = new BigDocument("Big Document # " + i); } else { folder[i] = new LittleDocument("Little Document # " + i); } }
如果Little Document没有继承Read(), 直接调用会有Exception。
foreach (Document doc in folder) { IStorable isDoc = doc as IStorable; if (isDoc != null) { isDoc.Read(); }
else
{ Console.WriteLine("IStorable not supported");
} //… }
这个例子简单明了
显式实现接口:
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace ConsoleApplication2 { class Program { interface IStorable { void Read(); void Write(); } interface ITalk { void Talk(); void Read(); } public class Document : IStorable, ITalk { public void Read() { Console.WriteLine("Read"); } public void Write() { Console.WriteLine("Write"); } void ITalk.Read() { Console.WriteLine("Read of ITalk"); } public void Talk() { Console.WriteLine("Talk"); } } static void Main(string[] args) { Document doc1 = new Document(); doc1.Read(); ITalk doc2 = doc1; doc2.Read(); } } }
1. 显式实现不用public
2. 显式调用需要新建ITalk对象(见代码)。
二、Array
新建由(2,3)开始的3x5的数组:
int[] lengthsArray = new int[2] { 3, 5 };
int[] boundsArray = new int[2] { 2, 3 };
Array multiDimensionalArray = Array.CreateInstance(typeof(string), lengthsArray, boundsArray);