Android Architecture Components Basic Sample

This sample showcases the following Architecture Components:

• Room
• ViewModels
• LiveData
• RxJava-RxAndroid

Introduction

Features

This sample contains two screens: a login view and a home view.

The app uses a Model-View-ViewModel (MVVM) architecture for the presentation layer. Each of the fragments corresponds to a MVVM View. The View and ViewModel communicate using LiveData and the following design principles:

• ViewModel objects don't have references to activities, fragments, or Android views. That would cause leaks on configuration changes, such as a screen rotation, because the system retains a ViewModel across the entire lifecycle of the corresponding view.

• ViewModel objects expose data using LiveData objects. LiveData allows you to observe changes to data across multiple components of your app without creating explicit and rigid dependency paths between them.

• Views, including the fragments used in this sample, subscribe to corresponding LiveData objects. Because LiveData is lifecycle-aware, it doesn’t push changes to the underlying data if the observer is not in an active state, and this helps to avoid many common bugs. This is an example of a subscription:

        // Update the list of products when the underlying data changes.
        viewModel.getProducts().observe(this, new Observer<List<ProductEntity>>() {
            @Override
            public void onChanged(@Nullable List<ProductEntity> myProducts) {
                if (myProducts != null) {
                    mBinding.setIsLoading(false);
                    mProductAdapter.setProductList(myProducts);
                } else {
                    mBinding.setIsLoading(true);
                }
            }
        });

Data layer

The database is created using Room