Tag: Android

Services

Services are Android Framework components meant for running background tasks that don’t need a visual component, therefore they do not provide a User Interface (UI). An Activity can start a Service which can then continue to run, even after the Activity is shut down. They are ideal for loading and processing data in the background, regardless of whether any of the app’s Activities are open. A common example of this is how you can receive notifications when an app is not running.

A Service should be used when the task is decoupled from (does not directly affect) the UI, and needs to exist even when there is no UI.

There are 3 ways to start a Service:

  • Start – manually from a context e.g. Activity. Executes but will not normally communicate back to the component that started it.
  • Schedule – if you want to have a Service execute at some point in the future, or when some conditions are met, you can create a JobService. You can control when this starts via a Scheduler e.g. JobScheduler
  • Bind – offers a client-server-like interface, with the Service being the server, and the various components being bound to the Service being the clients. Components bind to the Service via the bindService() method. These Services can easily communicate with the components that are bound to them (unlike the started Services above). An example might be an audio player, where the Service plays the audio while the Activity controls the UI, with the UI being updated as to the progress of the audio file play. Likewise, pressing the Pause button will mean sending a command to the Service.

A Service can be both STARTED and BOUND.

If you want to run a Service in a completely separate thread you can use an Intent Service.

The Lifecycle of a Started Service is depicted below:

Add Android Architecture Component Dependencies

To add the desired elements of Android Jetpack to your app. These will need to be updated as the version numbers increment.

Use the following in your build.gradle:
Futures
dependencies {
    def futures_version = "1.0.0-alpha02"

    implementation "androidx.concurrent:concurrent-futures:$futures_version"
}



Lifecycle AndroidX


dependencies {
    def lifecycle_version = "2.0.0"

    // ViewModel and LiveData
    implementation "androidx.lifecycle:lifecycle-extensions:$lifecycle_version"
    // alternatively - just ViewModel
    implementation "androidx.lifecycle:lifecycle-viewmodel:$lifecycle_version" // use -ktx for Kotlin
    // alternatively - just LiveData
    implementation "androidx.lifecycle:lifecycle-livedata:$lifecycle_version"
    // alternatively - Lifecycles only (no ViewModel or LiveData). Some UI
    //     AndroidX libraries use this lightweight import for Lifecycle
    implementation "androidx.lifecycle:lifecycle-runtime:$lifecycle_version"

    annotationProcessor "androidx.lifecycle:lifecycle-compiler:$lifecycle_version" // use kapt for Kotlin
    // alternately - if using Java8, use the following instead of lifecycle-compiler
    implementation "androidx.lifecycle:lifecycle-common-java8:$lifecycle_version"

    // optional - ReactiveStreams support for LiveData
    implementation "androidx.lifecycle:lifecycle-reactivestreams:$lifecycle_version" // use -ktx for Kotlin

    // optional - Test helpers for LiveData
    testImplementation "androidx.arch.core:core-testing:$lifecycle_version"
}



Lifecycle pre-AndroidX


dependencies {
    def lifecycle_version = "1.1.1"

    // ViewModel and LiveData
    implementation "android.arch.lifecycle:extensions:$lifecycle_version"
    // alternatively - just ViewModel
    implementation "android.arch.lifecycle:viewmodel:$lifecycle_version" // use -ktx for Kotlin
    // alternatively - just LiveData
    implementation "android.arch.lifecycle:livedata:$lifecycle_version"
    // alternatively - Lifecycles only (no ViewModel or LiveData).
    //     Support library depends on this lightweight import
    implementation "android.arch.lifecycle:runtime:$lifecycle_version"

    annotationProcessor "android.arch.lifecycle:compiler:$lifecycle_version" // use kapt for Kotlin
    // alternately - if using Java8, use the following instead of compiler
    implementation "android.arch.lifecycle:common-java8:$lifecycle_version"

    // optional - ReactiveStreams support for LiveData
    implementation "android.arch.lifecycle:reactivestreams:$lifecycle_version"

    // optional - Test helpers for LiveData
    testImplementation "android.arch.core:core-testing:$lifecycle_version"
}



Room AndroidX


dependencies {
    def room_version = "2.1.0-alpha03"

    implementation "androidx.room:room-runtime:$room_version"
    annotationProcessor "androidx.room:room-compiler:$room_version" // use kapt for Kotlin

    // optional - RxJava support for Room
    implementation "androidx.room:room-rxjava2:$room_version"

    // optional - Guava support for Room, including Optional and ListenableFuture
    implementation "androidx.room:room-guava:$room_version"

    // optional - Coroutines support for Room
    implementation "androidx.room:room-coroutines:$room_version"

    // Test helpers
    testImplementation "androidx.room:room-testing:$room_version"
}



Room pre-AndroidX


dependencies {
    def room_version = "1.1.1"

    implementation "android.arch.persistence.room:runtime:$room_version"
    annotationProcessor "android.arch.persistence.room:compiler:$room_version" // use kapt for Kotlin

    // optional - RxJava support for Room
    implementation "android.arch.persistence.room:rxjava2:$room_version"

    // optional - Guava support for Room, including Optional and ListenableFuture
    implementation "android.arch.persistence.room:guava:$room_version"

    // Test helpers
    testImplementation "android.arch.persistence.room:testing:$room_version"
}



Paging AndroidX


dependencies {
    def paging_version = "2.1.0-rc01"

    implementation "androidx.paging:paging-runtime:$paging_version" // use -ktx for Kotlin

    // alternatively - without Android dependencies for testing
    testImplementation "androidx.paging:paging-common:$paging_version" // use -ktx for Kotlin

    // optional - RxJava support
    implementation "androidx.paging:paging-rxjava2:$paging_version" // use -ktx for Kotlin
}



Paging pre-AndroidX


dependencies {
    def paging_version = "1.0.0"

    implementation "android.arch.paging:runtime:$paging_version"

    // alternatively - without Android dependencies for testing
    testImplementation "android.arch.paging:common:$paging_version"

    // optional - RxJava support
    implementation "android.arch.paging:rxjava2:$paging_version"
}



Navigation


dependencies {
    def nav_version = "1.0.0-alpha09"

    implementation "android.arch.navigation:navigation-fragment:$nav_version" // use -ktx for Kotlin
    implementation "android.arch.navigation:navigation-ui:$nav_version" // use -ktx for Kotlin
}



Work Manager


dependencies {
    def work_version = "1.0.0-beta02"

    implementation "android.arch.work:work-runtime:$work_version" // use -ktx for Kotlin+Coroutines

    // optional - RxJava2 support
    implementation "android.arch.work:work-rxjava2:$work_version"

    // optional - Test helpers
    androidTestImplementation "android.arch.work:work-testing:$work_version"
}



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