Incremental construction framework is a tool for optimizing the software construction process. It can redefine the part of the change according to the existing construct results, thereby improving the efficiency of the construction.In the Java class library, the implementation principle of incremental construction framework mainly includes the following aspects. First, the incremental construction framework needs to track the change of the source code based on a certain mechanism.A common mechanism is to mark the final modification time of the file using the timestamp of the file.For example, in Java, the final modification time of the file can be obtained through the `LastModified` method of the` File` class, and then compare it with the previous construction results to determine whether it is necessary to re -construct. Secondly, the incremental construction framework needs to be able to identify the part of the change.A common method is to compare the different versions of the source code using the source code version control system (such as Git, SVN, etc.), and then build an incremental construction based on the file list of the change.For example, through the git command `git diff`, you can obtain the file difference information between the two versions, and then decide whether to re -build the relevant class library based on the differential information. In addition, the incremental construction framework also needs to be able to intelligently identify the construction dependency relationship and update the corresponding update.In Java, you can manage the dependencies by using the construction tool (such as Maven, Gradle, etc.).These construction tools usually provide a mechanism from motion recognition dependency relationship, and only build only parts that need to be updated.For example, Maven will automatically identify modules or projects that need to be rebuilt through the dependency management mechanism in the POM file. In addition, an incremental construction framework also needs to provide an effective construction strategy to minimize unnecessary construction operations as much as possible.For example, the strategy of incremental compilation can be used to compile only the files that occur, rather than re -compile the entire project.In Java, you can identify changing files through the plug -in mechanism of the compiler, and only compile these files.For example, using the Java compiler API, you can get the AST (abstract syntax tree) of the Java source file, so as to identify whether the file needs to be re -compiled. Finally, in order to improve the efficiency of incremental construction, incremental construction frameworks usually use parallel construction methods.This means that multiple modules or projects can be constructed at the same time, thereby reducing the time consumption of the construction process.In Java, a concurrent programming framework (such as Java multi -thread, thread pool, etc.) can be used to achieve parallel construction.For example, the construction task can be divided into multiple sub -tasks, and these sub -tasks can be performed using the thread pool to achieve parallel construction. In summary, the implementation principle of incremental construction framework in the Java class library mainly includes the change of the change source code, the identification change part, the management construction dependencies, the use of effective construction strategies, and parallel construction.The application of these principles can greatly improve the efficiency of construction and reduce unnecessary construction operations, thereby speeding up the speed and quality of software development. The following is a simple Java code example. It demonstrates how to use an incremental construction framework to monitor the changes of the file and perform an incremental construction: ```java import java.io.File; public class IncrementalBuildFramework { private long lastBuiltTime; public void build() { File sourceDir = new File("src"); long currentModifiedTime = getLastModifiedTime(sourceDir); if (lastBuiltTime == 0 || currentModifiedTime > lastBuiltTime) { // Make incremental construction operation System.out.println ("re -construct"); // Update the final construction time lastBuiltTime = currentModifiedTime; } else { System.out.println ("No need to re -build"); } } private long getLastModifiedTime(File dir) { long lastModifiedTime = 0; for (File file : dir.listFiles()) { if (file.isDirectory()) { lastModifiedTime = Math.max(lastModifiedTime, getLastModifiedTime(file)); } else { lastModifiedTime = Math.max(lastModifiedTime, file.lastModified()); } } return lastModifiedTime; } public static void main(String[] args) { IncrementalBuildFramework buildFramework = new IncrementalBuildFramework(); // The first construction buildFramework.build(); // The simulation file changes File modifiedFile = new File("src/Example.java"); modifiedFile.setLastModified(System.currentTimeMillis()); // The second constructed buildFramework.build(); } } ``` In the above examples, the `IncrementalBuildFramework` class determines whether it is necessary to re -build through the final modification time of the file in the comparison source code directory.After the first construction, if the simulated file is modified, the change will be detected and the corresponding re -construction operation will be performed when it is built again.

In -depth analysis of the source code and internal implementation of the Spring ASM framework introduction: Spring is a popular Java development framework. It provides a lightweight IOC (INVERSION of Control, control reversal) and AOP (Aspect Oriented Programming) container to help developers build maintenance and extended can be expandable.s application.Among them, ASM (abstract syntax tree) framework is a core component of the Spring framework for generating, conversion and operation Java bytecode during runtime.This article will analyze the source code of the Spring ASM framework and its internal implementation. 1. Introduction to ASM framework: 1.1 What is the ASM framework? ASM is a lightweight Java bytecode operation and analysis framework. It provides some APIs and tools that can directly access the byte code to achieve the generation, conversion and analysis of bytecode.Compared with the reflex mechanism of Java, ASM can operate at the level of bytecode, with higher performance and more flexible performance. 1.2 Features of ASM framework: -The high performance: The ASM framework saves the reflected expenses by directly operating byte code, providing a higher performance bytecode generating and conversion. -Feilicity: The ASM framework provides the underlying API, allowing developers to finely control the byte code, can generate any complex bytecode, and can modify and adjust the existing bytecode. -Al lightweight: The core library of the ASM framework is very small. It does not rely on other third -party libraries, which can easily integrate into various applications. Second, internal implementation of ASM framework: 2.1 bytecode generation: The ASM framework can achieve bytecode generating by accessing and modifying the method in the classWriter class.The ClassWriter class provides a series of methods that can add classes, fields, methods, and operating instructions to the byte code.Below is a simple example. Demonstrate how to use the ASM framework to generate a heet code of the HelloWorld class: ```java ClassWriter classWriter = new ClassWriter(ClassWriter.COMPUTE_FRAMES); classWriter.visit(Opcodes.V1_8, Opcodes.ACC_PUBLIC, "com/example/HelloWorld", null, "java/lang/Object", null); MethodVisitor methodVisitor = classWriter.visitMethod(Opcodes.ACC_PUBLIC, "sayHello", "()V", null, null); methodVisitor.visitCode(); methodVisitor.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;"); methodVisitor.visitLdcInsn("Hello World!"); methodVisitor.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false); methodVisitor.visitInsn(Opcodes.RETURN); methodVisitor.visitMaxs(2, 1); methodVisitor.visitEnd(); classWriter.visitEnd(); byte[] byteCode = classWriter.toByteArray(); ``` The above code generates an open class called `com.example.helllowOrlow` in the ClassWriter class. This class has an openless` Sayhello` method, and the method is printed "Hello World!". 2.2 bytecode conversion: The ASM framework also provides many VISITOR classes for operation and conversion classes, fields, methods and instructions at the bytecode level.We can achieve customized bytecode conversion logic by inheriting these VISITOR classes.Below is a simple example, showing how to use ASM framework to convert bytecode. ```java ClassReader classReader = new ClassReader(byteCode); ClassWriter classWriter = new ClassWriter(ClassWriter.COMPUTE_FRAMES); classReader.accept(new ClassVisitor(Opcodes.ASM8, classWriter) { @Override public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) { super.visit(version, access, name, signature, superName, interfaces); // Modify the category name NewhellowORLD classWriter.visit(Opcodes.V1_8, access, "com/example/NewHelloWorld", signature, superName, interfaces); } @Override public MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) { MethodVisitor mv = super.visitMethod(access, name, descriptor, signature, exceptions); if (name.equals("sayHello")) { // Modify the method of the Sayhello method, change the original string to "Hello, the world!" mv.visitCode(); mv.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;"); mvisitldcinsn ("Hello, the world!"); mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false); mv.visitInsn(Opcodes.RETURN); mv.visitMaxs(2, 1); mv.visitEnd(); } return mv; } }, 0); byte[] newByteCode = classWriter.toByteArray(); ``` The above code reads the byte code generated before through classReader, and then uses the ClassWriter to convert the byte code read.In the `visit` method, we modified the class named` com.example.newhelllowOrld`.In the `visitmethod` method, we found the` Sayhello` method that was generated before, and modified its method to print "Hello, the world!".In the end, the modified bytecode `newbytecode` was obtained through the method of` ClassWriter.tobytearray (). in conclusion: Through in -depth analysis of the Spring ASM framework source code, we learned how the ASM framework generates, converts, and operates Java bytecode during runtime.The high -performance, flexibility and lightweight characteristics of the ASM framework make it an indispensable component in the Spring framework.Mastering the source code and internal implementation of the ASM framework will help better understand the working principle of the Spring framework, and can use the ASM framework to implement custom byte code operations. Note: The example code in this article is only to demonstrate the basic usage of the ASM framework. The actual use may involve more complex operations and scenes.

How to use Android Support Library custom view in the Java library Introduction: Android Support Library is a set of compatible libraries, which aims to provide developers with a backward compatibility function and UI interface for developers.In this article, we will introduce how to use Android Support Library in the Java library to create a custom view. step: 1. Add the support library dependency item: Add the following dependencies to your Java project's Build.gradle file: ```java dependencies { implementation 'com.android.support:support-v4:29.0.0' implementation 'com.android.support:appcompat-v7:29.0.0' } ``` This will ensure that you can use a class in Android Support Library to create a custom view. 2. Create a custom view class: Create a new Java class and inherit the View class in Android Support Library.For example, we create a customized ButtonView class: ```java import android.content.Context; import android.support.v7.widget.AppCompatButton; public class ButtonView extends AppCompatButton { public ButtonView(Context context) { super(context); // Perform the initialization of custom views here } } ``` In this example, we created a ButtonView class inherited from AppCompatButton. 3. The use of custom view: When using a custom view in your project, you can declare and use it in the XML layout file like other views.For example, in an activity_main.xml file, add the ButtonView View: ```xml <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent"> <com.example.myapp.ButtonView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Custom Button" /> </LinearLayout> ``` In this example, we use the custom ButtonView as a normal button. Summarize: Using Android Support Library can easily create a custom view in the Java library.By following the above steps, you can add the required dependencies, create a custom view class, and use them in the XML layout file.In this way, you can create a custom view compatible with Android applications in the Java library.

The Android support library is a group of compatibility libraries and tools on the Android devices provided by different versions.One of the important components is Android Support Library. Android Support Library provides a large number of customized views that enable developers to create a unique user interface according to their needs.This article will introduce how to use SUPPORT LIBRARY in Android applications to define viewing and provide some Java code examples. The first step of using the SUPPORT LIBRARY to customize the view is to ensure that your project already contains the required SUPPORT LIBRARY.It can be achieved by adding dependencies in the project's Build.gradle file.As follows: ```gradle implementation 'com.android.support:appcompat-v7:28.0.0' implementation 'com.android.support:design:28.0.0' ``` Once I introduced the support library, you can start custom view.The following is an example that shows how to create a button with a custom background color and text: ```java import android.content.Context; import android.support.v7.widget.AppCompatButton; import android.util.AttributeSet; public class CustomButton extends AppCompatButton { public CustomButton(Context context) { super(context); init(); } public CustomButton(Context context, AttributeSet attrs) { super(context, attrs); init(); } public CustomButton(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); init(); } private void init() { setBackgroundColor(getResources().getColor(R.color.custom_button_background)); setText("Click me"); } } ``` In the above example, we created a custom button class called CustomButton, which inherited from the AppCompatButton class.We have rewritten three constructors and call an init () method in each constructor.In the init () method, we set the custom background color and text for the button. To use the custom button in the layout file, just declare it like using a normal button.For example: ```xml <com.example.myapp.CustomButton android:layout_width="wrap_content" android:layout_height="wrap_content" /> ``` In this way, you can use the SUPPORT LIBRARY to define other types of views, such as text boxes, image views, etc. Android Support Library provides a rich custom view function that can meet the unique design needs of developers.This article provides a simple example, and introduces how to use the SUPPORT LIBRARY in the Android application.I hope this article can help you start using Android Support Library for custom view development.

Steps to customize views with Android Support Library: 1. Introduce dependency library In the built.gradle file of the project, add the following dependencies to introduce Android Support Library: ```gradle implementation 'com.android.support:appcompat-v7:28.0.0' ``` 2. Create a custom view class Create a new Java class and inherit the AppCompatimageView or AppCompattextView class.These classes are supporting backward view components provided by Android Support Library. For example, create a customized ImageView: ```java public class CustomImageView extends AppCompatImageView { // Add custom attributes and methods } ``` 3. Implement the structural method Implement the structure method in a custom view class.At least need to implement a constructor with a Context parameter.This parameter is used to pass the Context object to the parent class when the view instantiated. For example, to implement a customized imageView constructor: ```java public CustomImageView(Context context) { super(context); // Further initialization } ``` 4. Implement other methods and functions required In a custom view class, other methods and functions that other required methods and functions can be implemented according to the needs.For example, you can add custom attributes, handle clicks, and rewrite drawing methods. For example, add a custom attribute: ```java private int customAttribute; public void setCustomAttribute(int value) { customAttribute = value; } public int getCustomAttribute() { return customAttribute; } ``` 5. Use a custom view in the layout file In the XML layout file, you can use a custom view like other views.Just specify the complete class name as a label. For example, using custom ImageView: ```xml <com.example.app.CustomImageView android:id="@+id/custom_image_view" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/image" app:customAttribute="123" /> ``` 6. Use a custom view in the code In the Java code, you can use a custom view like an ordinary view.You can obtain instances through the FindViewByid method and call the corresponding method and attributes. For example, using custom ImageView: ```java CustomImageView customImageView = findViewById(R.id.custom_image_view); customImageView.setCustomAttribute(456); ``` In this way, you can use Android Support Library to create a custom view component. Note: The above steps are a basic process, and the actual demand may be different.

DEKATE :: Annotations :: Kubernetes framework and practice Kubernetes is a popular container arrangement platform with the ability to automate deployment, extend and manage applications.With the popularity of Kubernetes, it is important to provide developers with convenient deployment and management applications.In Kubernetes, using annotations is an effective way to define and configure the behavior and attributes of the application.In this article, we will understand the annotation examples and practice in the DekoRate framework to help developers better use Kubernetes for application deployment and management. DEKATE is an open source Java library, which aims to simplify the process of using Java to write applications in Kubernetes.It provides a set of annotations to bind the metadata of Kubernetes resources with the Java code to automatically generate the corresponding Kubernetes deployment list file.By using the DEKORATE framework, developers can configure and customize the Kubernetes resources of the application through annotations, and automatically generate the correct deployment list file for the application. The following is some commonly used annotation examples and practice in the DekoRate framework: 1. @Application: The starting point for defining a Kubernetes application.The annotation contains metadata such as the name, version, and mirroring strategies of the application.For example: ```java @Application(name = "my-app", version = "1.0.0", buildType = BuildType.Jvm) public class MyApp { public static void main(String[] args) { // The entry point of the application } } ``` 2. @Service: The configuration of a Kubernetes service is defined.The annotation includes the name, port number, type and other metadata of the service.For example: ```java @Service(name = "my-service", port = 8080, type = ServiceType.NodePort) public class MyService { } ``` 3. @Exposing: It is used to define the configuration of a Kubernetes revealing service.The annotation is used to specify the ports and access protocols of the application.For example: ```java @Exposing(port = 8080, protocol = Protocol.HTTP) public class MyService { } ``` 4. @Addlabel: Tags to add labels to Kubernetes resources.The annotation contains the label name and value to be added.For example: ```java @AddLabel(key = "app", value = "my-app") public class MyService { } ``` The above is just some commonly used annotations in the DekoRate framework. In fact, there are many other annotations that can be used to configure and customize Kubernetes resources.By using these annotations, developers can more conveniently define and manage the behavior and attributes of the application without manually writing a tedious Kubernetes deployment list file. In summary, the DekoRate framework provides a simple and powerful way to configure and customize the Kubernetes resources.By using these annotations, developers can reduce cumbersome allocation and improve production efficiency.It is hoped that this article will help developers who want to build and manage Java applications in Kubernetes.

ACORN framework introduction Overview: Acorn is a framework for rapid development of Java libraries. It provides some common problems solutions that enable developers to write and maintain code more efficiently.This article will introduce the main functions and usage methods of the ACORN framework, and provide some Java code examples to illustrate. Features: 1. Lightweight: ACORN framework is a lightweight library that does not have any additional overhead to the performance of the application. 2. Scalability: The Acorn framework provides many scalable interfaces and abstract classes, so that developers can customize functions and integrate into the framework according to their own needs. 3. High efficiency: The Acorn framework provides many optimization technologies, such as cache and concurrent control to improve the implementation efficiency of code. 4. Easy to use: The design goal of the Acorn framework is simple and easy to use, so that developers can quickly get started and develop quickly. The main function: 1. Object pool: The Acorn framework provides an efficient object pool for management and reuse objects.This can significantly improve the utilization of memory and performance.The following is an example of using an Acorn object pool: ``` // Create an object pool ObjectPool<String> stringPool = new ObjectPool<>(10, String::new); // Get the object from the object pool String str1 = stringPool.borrowObject(); // user target audience System.out.println(str1); // Put the object back to the object pool stringPool.returnObject(str1); ``` 2. Configuration management: The Acorn framework provides a flexible configuration management mechanism that allows developers to easily read and modify the configuration parameters.The following is an example of using ACORN configuration management: ``` // Load the configuration file ConfigManager.load("config.properties"); // Get the configuration parameter String url = ConfigManager.getString("database.url"); int port = ConfigManager.getInt("database.port"); // Modify the configuration parameter ConfigManager.setProperty("database.username", "admin"); ConfigManager.save("config.properties"); ``` 3. Abnormal processing: The Acorn framework provides a unified abnormal processing mechanism that allows developers to better process and record abnormal information.The following is an example of using Acorn anomalous treatment: ``` try { // Execute the code that may throw an abnormality // ... } catch (AcornException ex) { // Treatment abnormalities ex.printStackTrace(); Logger.error(ex.getMessage()); } ``` 4. Paimorizing control: The Acorn framework provides some concurrent control tools, so that developers can easily handle the problem of multi -threaded concurrent access.Here are an example of using ACORN concurrent control: ``` // Create a read and write lock ReadWriteLock lock = new ReentrantReadWriteLock(); // Read sharing resources lock.readLock().lock(); // Read operation lock.readLock().unlock(); // Write into shared resources lock.writeLock().lock(); // Write operation lock.writeLock().unlock(); ``` Summarize: The Acorn framework is a powerful tool for rapid development of the Java library. It provides many common problems solutions and enables developers to write and maintain code more efficiently.By using the ACORN framework, developers can focus more on the implementation of business logic without paying too much attention to the details of the bottom.

Android Support Library Custom View -Implementation of custom UI elements Introduction: Android Support Library is a set of development libraries to help Android developers easily achieve rich user interface and interactive experience.By using SUPPORT LIBRARY, developers can be compatible with extensive Android devices and use the latest Android features on older devices.This article will introduce how to use Android Support Library to achieve custom UI elements and provide some Java code examples to help you get started. Step 1: Create a custom view class To realize custom UI elements, we need to create a custom view class. This class will expand the appropriate view class provided by SUPPORT LIBRARY, such as `AppCompattextView`,` appCompatimageView`, etc.The following is a simple example to show how to create a custom circular image view: ```java import android.content.Context; import android.graphics.Canvas; import android.graphics.Paint; import androidx.appcompat.widget.AppCompatImageView; public class CircleImageView extends AppCompatImageView { private Paint circlePaint; public CircleImageView(Context context) { super(context); init(); } private void init() { // Initialized brush circlePaint = new Paint(); circlePaint.setColor(getResources().getColor(R.color.circle_color)); circlePaint.setAntiAlias(true); } @Override protected void onDraw(Canvas canvas) { // Get view width and height int viewWidth = getWidth(); int viewHeight = getHeight(); // Calculate the radius of the circle int radius = Math.min(viewWidth, viewHeight) / 2; // Draw a circular background canvas.drawCircle(viewWidth / 2, viewHeight / 2, radius, circlePaint); // Call the parent class method to draw a picture super.onDraw(canvas); } } ``` Step 2: Use a custom view in the layout file In your layout file, you can use a custom view element like using other view elements.The following is an example: ```xml <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <com.example.myapplication.CircleImageView android:layout_width="100dp" android:layout_height="100dp" android:src="@drawable/my_image" /> </LinearLayout> ``` Step 3: Use a custom view By find the corresponding view in the Java code and operate it, you can use a custom view.The following is an example, showing how to use custom circular image views in Activity: ```java public class MainActivity extends AppCompatActivity { private CircleImageView circleImageView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Find the custom view circleImageView = findViewById(R.id.circle_image_view); // Set the click event circleImageView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // Treat the click event Toast.makeText (MainActivity.this, "Click the circular picture", toast.length_short) .show (); } }); } } ``` in conclusion: By using Android Support Library, you can easily achieve custom UI elements and add unique user interface to your application.This article provides an example to show how to create and use custom circular image views.You can further expand and modify the custom view according to your needs.I hope this article will help your Android development journey!

How to expand the custom view function in Android Support Library Overview: In Android development, custom view is a very useful way to create a unique and customized user interface.Android Support Library provides rich functions to expand custom views and can maintain compatibility on extensive Android devices.This article will introduce how to use Android Support Library to extend the custom view function and provide code examples.Here are some common custom view functions: 1. Attribute definition: Define some custom attributes for custom views to use in layout files or code.This can provide more flexibility for the view.The following is an example code: ```xml <resources> <declare-styleable name="CustomView"> <attr name="customColor" format="color"/> </declare-styleable> </resources> ``` 2. Measurement and layout: By rewriting onMeaSure () and onlyout () methods, the size and location of the custom view can be controlled.The following is an example code: ```java @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int widthSize = MeasureSpec.getSize(widthMeasureSpec); int heightSize = MeasureSpec.getSize(heightMeasureSpec); // Calculate the measurement size of the view as needed setMeasuredDimension(widthSize, heightSize); } @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { // Define the location and layout of the view here } ``` 3. Drawing: By rewriting the ONDraw () method, you can control the drawing of custom views.You can use Canvas and Paint objects for drawing operations.The following is an example code: ```java @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); Paint paint = new Paint(); // Perform drawing operations, such as drawing shape, text, etc. } ``` 4. Interaction: By handling touch events and gesture recognition, you can add interactive functions to custom view.The following is an example code: ```java @Override public boolean onTouchEvent(MotionEvent event) { // Touch the touch event, such as clicking, sliding, etc. return super.onTouchEvent(event); } @Override public boolean onInterceptTouchEvent(MotionEvent event) { // Treatment of incident interception, such as handling touch events in the father's view return super.onInterceptTouchEvent(event); } ``` 5. Custom view combination: Create a more complex custom view through combination of multiple existing views or layouts.The following is an example code: ```java public class MyCustomView extends RelativeLayout { public MyCustomView(Context context) { super(context); initView(context); } public MyCustomView(Context context, AttributeSet attrs) { super(context, attrs); initView(context); initAttributes(attrs); } private void initView(Context context) { LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); inflater.inflate(R.layout.my_custom_view, this, true); } private void initAttributes(AttributeSet attrs) { // Analysis of custom attributes } } ``` Through these methods, we can use custom view features in Android Support Library to expand our application.These features can help us achieve highly customized user interfaces on different Android devices and provide a better user experience.Hope this article will be helpful for your expansion of the custom view function. Reference link: - https://developer.android.com/guide/topics/ui/custom-components - https://developer.android.com/training/custom-views

AndroidX is an Android development support library that provides developers with component, and the Preference framework is one of them.This article will explore the technical principles of the AndroidX Preference framework in the Java class library and provide some Java code examples. The AndroidX Preference framework helps developers to quickly build a setting page in the user interface.It provides a set of UI components that are easy to use and highly customable, such as multiple selection boxes, single -selected boxes, sliders, etc., while supporting read -write operations of persistent data.By using this framework, developers can easily create, manage and display various preference settings. First, we need to introduce the dependence of the AndroidX Preference framework in Gradle: ```java implementation 'androidx.preference:preference:1.1.1' ``` Before using the Preference framework, we need to define a class that inherits from PreferenceFragmentCompat.This class will be the main entrance point of our settings page.For example, we can create a class called Settingsfragment: ```java public class SettingsFragment extends PreferenceFragmentCompat { @Override public void onCreatePreferences(Bundle savedInstanceState, String rootKey) { setPreferencesFromResource(R.xml.preferences, rootKey); } // Add other custom methods and logic } ``` Then we need to create a XML file to define our preference settings page.This file will contain a variety of different Preference elements, such as SwitchPreference, ListPreference, etc.For example, we can create a file called Preferences.xml: ```xml <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"> <SwitchPreference android:key="notifications" Android: Title = "Receive Notice" Android: Summary = "Enable or Disable Notice" android:defaultValue="true" /> <ListPreference android:key="language" Android: Title = "Language Settings" Android: Summary = "Select your preferred language" android:entries="@array/language_options" android:entryValues="@array/language_values" android:defaultValue="en" /> // Add other Preference elements </PreferenceScreen> ``` Each preference element in XML has a unique key attribute to identify the preference.When the user changes the settings, we can use this key to obtain or save the value of the preference settings. Next, in our Activity or Fragment, we can instantly instance the SettingsFragment class and display it in the user interface: ```java public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); getSupportFragmentManager() .beginTransaction() .replace(R.id.container, new SettingsFragment()) .commit(); } // Add other custom code and logic } ``` Now, when we run the application, we will see a interface that contains our definition settings.Users can change the settings by interacting with these UI elements, and these changes will be preserved for a long time. Through the above code example, we can see some of the main principles of the AndroidX Preference framework.First of all, we define the structure and characteristics of the preference for setting the page.We then associate these definitions with the UI components provided in the Preference framework.Finally, we display these UI components in the user interface and handle the user's interactive operation. To sum up, the technical principles of the AndroidX Preference framework in the Java class library include defining the structure of the preference to set the page, using the PreferenceFragmentCompat class as the entrance point, creating the XML file to define the UI component of the settings page, the key and value of the associated UI component and the preference settings settingsAnd instantiated in Activity or Fragment and show the PreferenceFragment.By understanding these principles, developers can better use the Preference framework to create user -friendly settings pages.