c# Get object property from ArrayList

Question

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?)

Don't use arraylists in .net 2.0 and later.

Joel Coehoorn
– Joel Coehoorn

2010-09-08 16:08:20 +00:00
Commented Sep 8, 2010 at 16:08 — Joel Coehoorn
– Joel Coehoorn, Commented Sep 8, 2010 at 16:08

JaredPar · Accepted Answer · 2010-09-08 15:35:58Z

11

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

answered Sep 8, 2010 at 15:35

JaredPar

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Comments

Aliostad · Accepted Answer · 2010-09-08 15:37:07Z

1

try:

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

Needs to be casted from the type object.

answered Sep 8, 2010 at 15:37

Aliostad

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Comments

Brian Genisio · Accepted Answer · 2010-09-08 15:42:25Z

0

Just to get this code up with modern idioms:

public ArrayList productImages = new ArrayList();

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

can be re-written as:

var productImages = new List<ProductImage> { new ProductImage { ImageID = 123 } };

answered Sep 8, 2010 at 15:42

Brian Genisio

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1 Comment

Tom Gullen Over a year ago

Thanks, but I reduced the code in the question for simplicity, the actual code is in a loop getting database records

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