Android dynamically creating UI v. ListView

Question

I have an android app that I'm developing using Xamarin. The app contacts the server and, via web service (SOAP), receives a list of objects. Currently, in my axml file I have just linear layout (ll) within scrollview tags and nothing else. In the code, I loop through the collection and new up the elements that I want and attach it to a layout. Once I'm done with each record, I attach (i.e.AddView) to the master layout (ll). Everything works.

I have a couple of concerns and I appreciate some feedback on it.

1) Each object in the list contains an URL to an image online. Currently, for each object, my process downloads the picture individually. Would ListView give me any advantage of reusing (caching , etc.) an already downloaded picture even though other attributes of the objects are different? Will there be any gain in terms of network utilization if I switch to ListView?

2) Is drawing elements by hand (like I'm doing) an acceptable best-practice?

Thanks all.

Answer 1

Definitely use a ListView. There is a great article here by Lucas Rocha that outlines exactly why ListViews are beneficial and how to make them perform even better. To give you a few examples, ListViews minimize the number of view inflations you do, and they only create the list items currently visible on the screen or about to become visible on the screen.

This is a huge improvement from your approach, since your current method would load every element in the list before presenting the activity to the user. Therefore, drawing elements by hand like you're currently doing is definitely not best-practice.

Also, for displaying images from URLs in your Xamarin app, I highly recommend that you use the Xamarin component UrlImageViewHelper. Despite being incredibly easy to implement in your app, it will improve performance drastically since it takes care of image caching and async image loading.