What is Android AAC?
Android Architecture Components (AAC) is a collection of official libraries designed to support Android app development. The purpose of AAC is to reduce the complexity of app development, increase stability, and provide easier handling of resource management and lifecycle events. The library is composed of several components, each providing the following functionalities:
- Lifecycle awareness: Automatically manages the lifecycle events of activities and fragments.
- Data binding: Automatically synchronizes UI and data, making it easier to write clean code.
- Storage support: Provides the Room library for easy use of Android data storage such as SQLite and Shared Preferences.
- Background task management: Offers WorkManager to manage background tasks, such as network requests.
These components work together to aid in effective Android app development. This is particularly beneficial as app development projects grow larger, helping to reduce the possibility of bugs when handling various states and lifecycle events. In conclusion, Android AAC is an excellent collection of libraries that make Android app development more streamlined and stable.
Main Components of Android AAC
Android AAC includes several components that support app development. The following is a brief description of the main components:
1. LiveData
LiveData is a lifecycle-aware observable data holder class. It automatically reflects changes in data to the UI and can be used in conjunction with the lifecycle of Activity and Fragment. This prevents issues such as memory leaks, updating terminated Activity, and incorrect handling of lifecycle events.
2. ViewModel
ViewModel is a class that stores and manages UI-related data, characterized by its ability to function without worrying about the lifecycle. As a result, it eliminates the need for cumbersome tasks to preserve data during screen rotation or Activity recreation and separates business logic from the View to improve readability.
3. Room
Room is an object-relational mapping library that implements data access objects (DAO) and data entities. It simplifies SQLite database work by abstracting complex code. Room detects issues at compile time to improve app stability and supports asynchronous operations using coroutines or RxJava.
4. Data Binding
By using the data binding library, UI components can be directly bound to a data model. This automatically handles UI updates and allows for clean code implementation without directly writing code for state changes.
5. WorkManager
WorkManager is a feature used to manage and coordinate background tasks. Depending on the user's environment, it manages the schedule of long-running or delayed background tasks, retries or combines tasks, and provides various other functions. This helps improve app performance and battery efficiency.
These main components come together to enable a fantastic Android app development process. Each element plays an important role in enhancing app performance and stability and makes project management and maintenance easier.
ViewModel Example for Lifecycle Management
Using ViewModel allows you to manage UI-related data independently of the Activity or Fragment's lifecycle. This makes it easier to maintain and manage data in situations such as screen rotation and Activity recreation. The following is a simple example using ViewModel:
1. Create ViewModel class
First, create a ViewModel-based class. This class should inherit from ViewModel and include the LiveData object you want to use.
class MainViewModel : ViewModel() {
val count: MutableLiveData<Int> = MutableLiveData()
fun increment() {
count.value = (count.value ?: 0) + 1
}
fun decrement() {
count.value = (count.value ?: 0) - 1
}
}
2. Using ViewModel in Activity
In the Activity, use ViewModelProvider to obtain a ViewModel instance. In this example, handle button click events and update the TextView value.
class MainActivity : AppCompatActivity() {
private lateinit var viewModel: MainViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
viewModel = ViewModelProvider(this).get(MainViewModel::class.java)
viewModel.count.observe(this, Observer {
findViewById<TextView>(R.id.tv_count).text = it.toString()
})
findViewById<Button>(R.id.btn_increment).setOnClickListener {
viewModel.increment()
}
findViewById<Button>(R.id.btn_decrement).setOnClickListener {
viewModel.decrement()
}
}
}
In this example, the MainViewModel's count value is increased or decreased each time the button is clicked, and the TextView value is automatically updated using LiveData. By leveraging ViewModel, managing an app's lifecycle becomes much more convenient.
UI Update Using Data Binding
By using the data binding library, you can combine UI components and data sources to create concise code and automate UI updates. The following example explains how to connect a ViewModel and UI using data binding.
1. Enable Data Binding
First, enable data binding in the app-level build.gradle.
android {
...
buildFeatures {
dataBinding true
}
}
2. Use Data Binding in Layout Files
Wrap the existing layout file with a <layout> tag and declare a ViewModel variable inside the <data> tag.
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<variable
name="viewModel"
type="com.example.myapplication.MainViewModel" />
</data>
...
</layout>
3. Bind View and ViewModel
Bind the view and ViewModel using the variables declared in the layout. In this example, display the count value of the ViewModel in the TextView.
<TextView
android:id="@+id/tv_count"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{Integer.toString(viewModel.count)}" />
4. Apply Binding in Activity
In the Activity, set up data binding using DataBindingUtil. In this process, assign the ViewModel to the layout variable.
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
private lateinit var viewModel: MainViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = DataBindingUtil.setContentView(this, R.layout.activity_main)
viewModel = ViewModelProvider(this).get(MainViewModel::class.java)
binding.viewModel = viewModel
binding.lifecycleOwner = this
// Set event listeners
...
}
}
In this example, the TextView is automatically updated whenever the count value of the ViewModel changes, using data binding. By leveraging data binding, UI code becomes much cleaner and productivity is enhanced.
WorkManager Example for Managing Background Tasks
WorkManager is a class used for managing and scheduling tasks that run in the background or have a delay. With WorkManager, you can control task execution times, retry on failure, and set various task conditions. Here's a simple example using WorkManager.
1. Define WorkManager Task
Define a class that abstracts the basic task and implement the abstract method doWork(). In this example, define a task that logs every 10 seconds.
class LogWorker(appContext: Context, workerParams: WorkerParameters) :
Worker(appContext, workerParams) {
override fun doWork(): Result {
Log.d("LogWorker", "Work executed: ${System.currentTimeMillis()}")
return Result.success()
}
}
2. Create Task Request
Create a periodic task request using PeriodicWorkRequest. In this example, request a task that runs every 10 seconds.
val request = PeriodicWorkRequestBuilder<LogWorker>(10, TimeUnit.SECONDS).build()
3. Register Task with WorkManager
Obtain an instance of WorkManager using the getInstance() method and register the task.
WorkManager.getInstance(applicationContext).enqueue(request)
In this example, you can easily register and manage tasks that run periodically in the background using WorkManager. Using WorkManager reduces the complexity of your app and allows for efficient scheduling of background tasks.
RecyclerView Example for Managing List Items
RecyclerView is a container for efficiently managing list items and displaying a scrollable view. By using RecyclerView, you can display a large number of data items and manage them efficiently for recycling. Here's a simple example using RecyclerView.
1. Define Data Class
First, define the data model class to be displayed in the list.
data class Item(val title: String, val description: String)
2. Define List Item Layout
Define the layout for each item in the RecyclerView. In this example, we use a simple layout with two text views.
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/tv_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/tv_description"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
3. Create RecyclerView Adapter
Define an adapter class for the RecyclerView and implement the ViewHolder. Override the onCreateViewHolder(), onBindViewHolder(), and getItemCount() methods.
class ItemAdapter(private val items: List<Item>) :
RecyclerView.Adapter<ItemAdapter.ItemViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ItemViewHolder {
val view = LayoutInflater.from(parent.context)
.inflate(R.layout.item_layout, parent, false)
return ItemViewHolder(view)
}
override fun onBindViewHolder(holder: ItemViewHolder, position: Int) {
holder.bind(items[position])
}
override fun getItemCount(): Int {
return items.size
}
class ItemViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
private val title: TextView = itemView.findViewById(R.id.tv_title)
private val description: TextView = itemView.findViewById(R.id.tv_description)
fun bind(item: Item) {
title.text = item.title
description.text = item.description
}
}
}
4. Use RecyclerView in Activity
Add a RecyclerView to the layout, and then connect and set the adapter and data in the Activity.
class MainActivity : AppCompatActivity() {
private lateinit var recyclerView: RecyclerView
private lateinit var adapter: ItemAdapter
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
recyclerView = findViewById<RecyclerView>(R.id.recyclerview)
recyclerView.layoutManager = LinearLayoutManager(this)
val items = generateItems()
adapter = ItemAdapter(items)
recyclerView.adapter = adapter
}
private fun generateItems(): List<Item> {
// Return desired list of items
}
}
Using this example, you can efficiently manage and display list items with RecyclerView. This can improve the performance and usability of apps that handle large data sets.
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