System.ArgumentOutOfRangeException:** 'Index was out of range. The Error is : Index was outside the bounds of the array

Question

Hello I am trying to pass a List of bytes arrays to method as parameter ,
this is the declaration : List<byte[]> listes= new List<byte[]>();

this is how i declared the method to call : MethodDeclare(List<byte[]> listes)
and this is how i called the methods :
Methodcall(listes)

But i get that exception , anyone know what is the reason please , any help ?

Answer 1

Hello,​

Welcome to our Microsoft Q&A platform!

I used your code, I got the same exception as yours.

I read the Image from URL, use Async/await method to read it, if you get exception, because you do not get all the byte[] completely, then you execute Bitmap bitmap1= BitmapFactory.DecodeByteArray(imageBytes1, 0, imageBytes1.Length); bitmap1 is empty, List<byte[]> images is empty as well, so you need to wait the image read completely, then this exception will disappear.

I use var result = Task.Run(async () => await Download("https://news.microsoft.com/wp-content/uploads/2014/12/452292672.jpg")).Result; to wait the Async/await method execute completely.

   List<byte[]> images;  
           protected override void OnCreate(Bundle savedInstanceState)  
           {  
               base.OnCreate(savedInstanceState);  
     
               Xamarin.Essentials.Platform.Init(this, savedInstanceState);  
               global::Xamarin.Forms.Forms.Init(this, savedInstanceState);  
               LoadApplication(new App());  
     
               images = new List<byte[]>();  
               AddData();  
     
               MotionDetected(images);  
     
           }  
     
           public async  void AddData()  
           {  
               
               var result = Task.Run(async () => await Download("https://news.microsoft.com/wp-content/uploads/2014/12/452292672.jpg")).Result;  
               var result2 = Task.Run(async () => await Download("https://news.microsoft.com/wp-content/uploads/2014/12/452292672.jpg")).Result;  
                
     
               images.Add(result);  
               images.Add(result2);  
               
           }  
           public async Task<byte[]> Download(string url)  
           {  
               using (HttpClient client = new HttpClient())  
               {  
                   byte[] fileArray = await client.GetByteArrayAsync(url);  
                   return fileArray;  
               }  
     
           }  
     
     
           public bool MotionDetected(List<byte[]> images)  
           {  
               byte[] imageBytes1 = images[0];  
               byte[] imageBytes2 = images[0];  
     
              Bitmap bitmap1= BitmapFactory.DecodeByteArray(imageBytes1, 0, imageBytes1.Length);  
              Bitmap bitmap2 = BitmapFactory.DecodeByteArray(imageBytes2, 0, imageBytes2.Length);  
     
     
               int heightFirstImage=bitmap1.Height;  
               int widthFirstImage = bitmap1.Width;  
     
               int heightSecondImage = bitmap2.Height;  
               int widthSecondImage = bitmap2.Width;  
     
               //ImageProcessing  
               AssetManager assets = this.Assets;  
     
                
     
               return true;  
           }  

Best Regards,

Leon Lu

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