aimilushev / imagesearch

ImageSearch application

This is a demo application showcasing an image search functionality. The data is retrieved from backend web service and is presented in a 3 column grid. The images count may be really big, so they are retrieved on chunks, simulating an infinite scroll. The data is retrieved from flickr API

Application dependencies

This application is integrating the latest android best practices. It's written in kotlin and is based on Android Jetpack components including:

• ViewModel
• LiveData
• Paging
• Lifecycle
• ConstraintLayout

Asyncronous tasks are made via kotlin coroutines. No 3rd party dependencies are used.

Application components and implementation details

UI

SearchFragment is the screen responsible for visualising the search bar and search results

Presentation

SearchViewModel is the viewModel feeding the fragment with search results and interacting with data layer to retrieve search results

Data

• NetworkPhotosDataSource: class implementing PhotosDataSource used to make network API calls.
• DefaultPhotosRepository: class implementing PhotosRepository used as a facade to hide data retrieving implementation. Currently it transparently calls NetworkPhotosDataSource, but can easily be extended to add some sort of caching with minimal changes adding another PhotosDataSource implementation
• PhotosPageDataSource : data source based on the Paging component used to retrieve data from the repository for the current or next "page" of photos

Others

• ImageLoader: class used for loading and caching images from the network
• JsonMapper: class used for json to object conversion
• Injector: class used to enhance dependency injection, giving the possibility to replace some implementations during tests

Unit tests

Unit tests are based on Junit 4, Mockito and Kotlinx Coroutines Test

Possible improvements

• Implement retry mechanism when a web service call fails
• Implement image cache on file system
• Add voice search and search suggestions
• Write some integration tests

imagesearch's Issues

Sometimes wrong image is loaded

Wrong image is loaded when we have a correct item at cache. The correct one is loaded and afterwards replaced with wrong one.
This is caused by :

1. When setting image from cache the image tag is not updated
2. When setting image from cache a pending download for this imageView is not cancelled