Architecture Components

This section is all about building the apps in a better and an easier way. Architecture components were launched in November 2017 with a prime motive of removing the difficulties faced by the developers in the common use cases scenarios which have been making our lives tough since forever. Basically, architecture components are the fundamental components on the top of which, applications can be built in an easier way. With the architecture components, the problems like difficulty in sharing of data between fragments and activities, loss of data due to orientation changes and other such problems were handled.

The architecture components have been brought in keeping the following points in mind:

• Solving the right problems To solve the problems that were faced by all the developers or things that are considered hard like for starters the activity lifecycle because if it is implemented incorrectly then nothing in the activity can work right. So, the need was observed and solutions to problems like these and other similar ones were developed to make the process of development easier and enjoyable.
• Playing well with others Developers invest too much in their codes, hence it wouldn't have been practical to ask everybody to start afresh. Therefore the changes were made keeping in mind that they could be incorporated with the existing code with only a little bit of effort.
• Apps should be scalable The app must work properly amidst the massive complexities of reality, it should not be like that it is working well on the emulator under the supervision of the developer but crashes when it goes out to the real people in the industry.
• Reach The usage of APIs needs to be minimized, therefore the capabilities of support libraries were increased.

Therefore, in simple words architecture components are a set of libaries that help in designing robust, testable, and maintainable apps. The components are as follows:

• Lifecycle, LifecycleOwner and LifecycleObsever This components automatically responds to the lifecycle events, thereby solving most of the lifecycle related issues.
• View Model This allows data to survive configuration changes because the data that is stored locally is unaffected by the UI of the app. Therefore, change in UI components when the app is rotated do not affect the data stored.
• Room It is an object mapping library for SQLite.
• Live Data They are the data objects that notify the views whenever the related database is changed.

All these components will be discussed in detail in the coming sections.

Adding Architecture Components

Android Studio projects aren't configured to access this repository by default.

To add it to your project, open the build.gradle file for the project and add the google() repository as shown below:

allprojects {
    repositories {
        google()
        jcenter()
    }
}

In the build.gradle file of your app, add the following dependecies:

dependencies {

    // ViewModel and LiveData
    implementation "android.arch.lifecycle:extensions:1.1.1"
    // alternatively, just ViewModel
    implementation "android.arch.lifecycle:viewmodel:1.1.1"
    // alternatively, just LiveData
    implementation "android.arch.lifecycle:livedata:1.1.1"

    annotationProcessor "android.arch.lifecycle:compiler:1.1.1"

    // Room (use 1.1.0-beta3 for latest beta)
    implementation "android.arch.persistence.room:runtime:1.0.0"
    annotationProcessor "android.arch.persistence.room:compiler:1.0.0"

    // Test helpers for LiveData
    testImplementation "android.arch.core:core-testing:1.1.1"

    // Test helpers for Room
    testImplementation "android.arch.persistence.room:testing:1.0.0"

}