Android Arch Runtime Framework in the Java Class Library Discussion
Android Arch Runtime Framework in the Java Class Library Discussion
Abstract: Android Arch Runtime is a framework for building a reliable, robust and maintaining Android application.This article introduces the application case of Android Arch Runtime framework in the Java library, which aims to help developers fully understand and use the various functions and advantages of the framework.
introduction:
Android Arch Runtime is a framework developed by Google to help developers build a reliable, robust and maintainable Android application.It provides a series of components to simplify the development of Android applications and improve the quality of the code structure by providing consistent architecture guidance throughout the life cycle of the application.In this article, we will explore the application cases of the Android Arch Runtime framework in the Java class library, and provide some code examples to illustrate its use method and advantages.
1. Framework Overview
The Android Arch Runtime framework contains a set of core components, the most important of which is LiveData, ViewModel, Room and DataBinding.These components can work well to achieve data observation and response updates, and at the same time provide simple and consistent APIs.
1. LiveData: LiveData is an observed data holder. It can perceive the life cycle and send notifications to the observer when the data is changed.Its application cases in the Java class library are very rich, especially when the UI is updated in real time or the results of the processing asynchronous task.The following is a simple code example:
LiveData<String> liveData = new MutableLiveData<>();
liveData.observe(this, new Observer<String>() {
@Override
public void onChanged(String value) {
// Update the UI here
}
});
2. ViewModel: ViewModel is used to store data related to the interface. It maintains the consistency of data when configuration changes (such as screen rotation).ViewModel can be combined with LiveData to provide observed data supply interfaces.The following is a simple code example:
public class MyViewModel extends ViewModel {
private MutableLiveData<String> data = new MutableLiveData<>();
public LiveData<String> getData() {
return data;
}
public void fetchData() {
// Asynchronously acquisition data and update DATA
}
}
3. Room: Room is a durable library for using the SQLITE database in Android applications.It provides a set of annotations to define database tables, query and relationships.The following is a simple code example:
@Entity(tableName = "users")
public class User {
@PrimaryKey
public int id;
public String name;
// ...
}
@Dao
public interface UserDao {
@Query("SELECT * FROM users")
List<User> getAllUsers();
@Insert
void insertUser(User user);
// ...
}
@Database(entities = {User.class}, version = 1)
public abstract class MyAppDatabase extends RoomDatabase {
public abstract UserDao userDao();
}
4. DataBinding: DataBinding is a library that can directly bind data in the layout file.It enables developers to reference data through expressions in the layout file and automatically generate code -related code.The following is a simple code example:
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<variable name="user" type="com.example.User" />
</data>
<TextView
android:text="@{user.name}"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</layout>
2. Application case:
The Android Arch Runtime framework has many application cases in the Java class library.Below we will introduce the two typical cases:
1. ViewModel + LiveData: In an application that needs to be updated in real time, you can use ViewModel and livedata to provide observed data supply interface use.Below is an example of displaying the current time:
public class MyViewModel extends ViewModel {
private MutableLiveData<String> time = new MutableLiveData<>();
public LiveData<String> getTime() {
return time;
}
public void updateTime() {
String currentTime = getCurrentTime();
time.setValue(currentTime);
}
}
2. Room + LiveData: Combining with Room and LiveData can easily handle database operations and notify UI to respond when the data is updated.The following is a simple user column to represent an example:
public class MyViewModel extends ViewModel {
private LiveData<List<User>> userList;
public LiveData<List<User>> getUserList() {
if (userList == null) {
// Query the database to get the user list
userList = getUserListFromDatabase();
}
return userList;
}
private LiveData<List<User>> getUserListFromDatabase() {
// Use Room to query the database to get the user list
}
}
in conclusion:
The Android Arch Runtime framework has many application cases in the Java class library, covering core components such as LiveData, ViewModel, Room, and DataBinding.By making full use of these components, developers can build a reliable, strong and easy -to -maintain Android application.It is hoped that the case introduced in this article can help readers better understand and apply Android Arch Runtime framework.
