C＃ArrayList中从获取对象的属性 [英] c# Get object property from ArrayList

问题描述

想不通这一个

我的班级一个ArrayList

  //保存图像
        公共类productImage
        {
            公众诠释imageID;
            公共字符串IMAGEURL;
            公众的DateTime dateAdded;
            公共字符串slideTitle;
            公共字符串slideDescrip;
        }    公共ArrayList的productImages =新的ArrayList（）;productImage newImage =新productImage（）;
newImage.imageID = 123;
productImages.Add（newImage）;
 

现在我怎么访问属性？

  INT东西= productImages [0] .imageID
 

不行！

  

错误1对象不包含
  定义slideTitle无
  扩展方法slideTitle
  接受类型的第一个参数
  对象可以找到（你
  缺少using指令或程序
  集引用？）

解决方案

在的ArrayList 被键入到对象的值。你需要转换为 productImage 来访问属性。

  INT东西=（（productImage）productImages [0]）imageId。
 

有一个更好的解决方案，虽然是使用强类型集合像列表＆LT; T＆GT; 。您可以指定元素类型是 productImage 并完​​全避免铸件。

 公开名单＆LT; productImage＆GT; productImages =新的List＆LT; productImage＆GT;（）;
productImage newImage =新productImage（）;
newImage.imageID = 123;
productImages.Add（newImage）;
INT东西= productImages [0] .imageID; //作品
 

Can't figure this one out

I have an ArrayList of classes:

        // Holds an image
        public class productImage
        {
            public int imageID;
            public string imageURL;
            public DateTime dateAdded;
            public string slideTitle;
            public string slideDescrip;
        }

    public ArrayList productImages = new ArrayList();

productImage newImage = new productImage();
newImage.imageID = 123;
productImages.Add(newImage);

Now how do I access the property?

int something = productImages[0].imageID

Doesn't work!

Error 1 'object' does not contain a definition for 'slideTitle' and no extension method 'slideTitle' accepting a first argument of type 'object' could be found (are you missing a using directive or an assembly reference?)

解决方案

The values in an ArrayList are typed to Object. You need to cast to productImage to access the property.

int something = ((productImage)productImages[0]).imageId;

A much better solution though is to used a strongly typed collection like List<T>. You can specify the element type is productImage and avoid the casting altogether.

public List<productImage> productImages = new List<productImage>();
productImage newImage = new productImage();
newImage.imageID = 123;
productImages.Add(newImage);
int something = productImages[0].imageID;  // Works

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