The technical principle of UJO ORM framework in the Java library UJO ORM (Object/Relational Mapping) is an open source Java framework to simplify the mapping operation between the Java object and the relationship database.Its technical principle is based on the Java's reflection mechanism and annotation function, providing a convenient way to handle the conversion between the object and the database, and realize the relevant database operation. The main technical principles of the UJO ORM framework are as follows: 1. Note and reflection mechanisms: UJO ORM uses Java's reflection mechanism and annotations to achieve the mapping and database operation of the object.By adding annotations to the Java class, developers can specify the mapping relationship between classes, the mapping relationship between fields and columns, and various attributes that define database operations.At the same time, UJO ORM can dynamically read and modify the attributes of the Java object during runtime, and map it to the corresponding fields in the database. 2. Database connection management: UJO ORM provides the management of database connection pools, reducing the overhead of the database connection.Developers can specify the relevant information of the database in the configuration file, including database types, drivers, connecting URLs and account passwords.UJO ORM will automatically establish a database connection based on these configuration information and provide a simple API to operate the database. 3. Object-Relationship mapping: UJO ORM uses the object-relationship mapping method to process the mapping relationship between the Java object and the database table.Developers can use annotations to specify the mapping relationship between objects and tables, and set the corresponding relationship between fields and columns.UJO ORM will automatically generate SQL statements based on the annotation configuration to realize data conversion between objects and databases. 4. Entity operation: UJO ORM provides a set of APIs to operate the entity increase, delete, change, and check.By using the unified interface provided by UJO ORM, developers can easily perform database operation without writing complex SQL statements.For example, you can save the entity into the database by calling the Save () method, or load the data in the database by calling the load () method to the corresponding entity object. Below is a sample code using the UJO ORM framework: ```java import org.ujorm.orm.*; public class User extends OrmTable<User> { @Column(pk = true) private Integer id; @Column(length = 50, uniqueIndex = "idx_username") private String username; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public static void main(String[] args) { OrmHandler handler = new OrmHandler(); ORMDECORATOR <account> orm = handler.orm (user.class); // Get the ONER class ORM operating object User user = new User(); user.setId(1); user.setUsername("Alice"); Orem.insert (user); // Insert user entities to database User loadedUser = ORM.SELECTBYID (1); // Load the user entity from the database through the ID System.out.println (loadeduser.getusername ()); // Output: "alice" } } ``` In the above sample code, we created a User class and used the annotation of the UJO ORM framework to specify the mapping relationship with the database table.In the main method, we used Ujo ORM's API for insertion and query operations. In short, the technical principle of the UJO ORM framework in the Java class library is based on the reflection mechanism and annotation function of Java. Through object-relationship mapping and database connection management, it provides a convenient way to handle the mapping relationship and database between the object and the database and the database.operate.By using UJO ORM, developers can develop database development more efficiently.

Uncharacteristic set refers to a collection that cannot be modified once it is created.The Java class library provides Jimmutable Collections (JIC) framework to create uncharacteristic sets. These sets can ensure the integrity and thread security of the data.This article will introduce the advantages, use methods, and Java code example of the JIC framework. First of all, let's find out why the useless collection is beneficial.There is the following advantages of non -changing collection: 1. Thread security: Since the uncharacteristic set cannot be modified, multiple threads can be accessed and used in parallel to use them without extra synchronization mechanisms. 2. Data integrity: The uncharacteristic set prevents unexpected data modification and ensures the consistency and reliability of the data. 3. Performance optimization: Because the unsatisfactory collection cannot be modified after creation, some optimization can be performed, such as sharing data internally to improve performance and memory efficiency. Next, let's see how to use the JIC framework in Java to create uncharacteristic sets.First, we need to add the dependency item of the JIC library.You can add it to the Maven or Gradle configuration file: Maven: ```xml <dependency> <groupId>org.javimmutable</groupId> <artifactId>jimmutable-collections</artifactId> <version>4.0.0</version> </dependency> ``` Gradle: ```groovy implementation 'org.javimmutable:jimmutable-collections:4.0.0' ``` Once the dependencies are added, we can start using the JIC framework to create uncharacteristic collection.The following are examples of some common JIC collection types and their creation methods: 1. JLIST (unsatisfactory list): ```java JList<String> list = JList.of("apple", "banana", "orange"); ``` 2. JMAP (unsatisfactory mapping): ```java JMap<String, Integer> map = JMap.of("apple", 1, "banana", 2, "orange", 3); ``` 3. JSET (non -changing collection): ```java JSet<Integer> set = JSet.of(1, 2, 3, 4, 5); ``` After creating these uncharacteristic sets, it cannot be added, deleted or modified.If you want to perform these operations, you can create a new unchanged collection. The benefits of using the JIC framework are not limited to the creation of inseparable collection.It also provides many convenient operation methods, such as mapping conversion, filtration and aggregation.Here are some examples: 1. Map conversion: ```java JList<Integer> transformedList = list.map(String::length); ``` 2. Filter: ```java JList<String> filteredList = list.filter(str -> str.startsWith("a")); ``` 3. Jugging: ```java int sum = set.fold(0, (acc, element) -> acc + element); ``` By using these methods, various operations can be performed on the inseparable collection without worrying about any impact on its original data. To sum up, the Jimmutable Collection (JIC) framework provides the ability to create uncharacteristic collection in Java.There are many benefits such as thread security, data integrity, and performance advantages.By using the JIC framework, we can create and operate these sets, and ensure the integrity and security of the data.This will make our code more robust and reliable. I hope this article can help you understand the JIC framework and the basic method of creating unchanged collection.Let us make full use of this powerful library when developing Java applications to improve code quality and performance.

Play Services GCM Technical Principles Analysis Play Services GCM (Google Cloud Messaging) is a cloud push service provided by Google, which allows developers to send messages and notifications to Android devices.This article will analyze Play Services GCM technical principles and provide Java code examples. 1. What is Play Services GCM? Play Services GCM is a cloud -based message transmission framework. Through the services provided by Google, a message push between the server and Android devices.It allows developers to send messages and notifications to devices registered with GCM services in order to interact with users in real time. 2. Play Services GCM working principle 1. Register GCM service On Android devices, developers need to use Google Play service SDK to register GCM service.After registration, the device will get a unique identifier (that is, register token) to send messages on the server. 2. Send a message to the GCM server Developers need to send the message to the GCM server.The message can be a combination of notifications, data or two.Each message contains a registered token of a target device. 3. The GCM server puts the message route to the target device After the GCM server receives the message, the message routing to the target device.After the device receives the message, it can customize the processing logic, such as displaying notifications or executing specific operations. 4. Send confirmation information to the GCM server After the device receives the message, send confirmation information to the GCM server.In this way, the GCM server knows that the news has been successfully delivered. 5. Optional ACK (Answe) message If the developer wants to pass the two -way message with the server, it can be implemented by sending ACK messages to the GCM server.ACK message carries custom data and sends it to the target device. 3. Java code example The following is an example of Java code using Play Services GCM: 1. Register GCM service ```java GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(context); String registrationToken = gcm.register(SERVER_APP_ID); ``` 2. Send a message to the GCM server ```java JSONObject message = new JSONObject(); message.put("title", "Hello"); message.put("body", "This is a GCM message"); String jsonString = message.toString(); HttpPost httpPost = new HttpPost(GCM_SERVER_URL); httpPost.setHeader("Authorization", "key=" + SERVER_API_KEY); httpPost.setHeader("Content-Type", "application/json"); httpPost.setEntity(new StringEntity(jsonString)); HttpClient client = new DefaultHttpClient(); HttpResponse response = client.execute(httpPost); ``` 3. The processing of the device after receiving the message ```java @Override public void onMessageReceived(String from, Bundle data) { String title = data.getString("title"); String body = data.getString("body"); // Show notification or process other logic } ``` Please note that the above code example is only the basic usage of GCM, not a complete implementation.In practical applications, appropriate error processing and network connection code need to be added. in conclusion Play Services GCM technology uses the cloud push service provided by Google to enable developers to send messages and notifications to Android devices.This article analyzes the working principle of Play Services GCM and provides related Java code examples.I hope this article can help readers better understand and use Play Services GCM.

Anthology JTA (Java Transaction API) framework is an important component for managing distributed transactions in the Java class library.It provides a mechanism for Java applications to ensure that the operation of multiple resources (such as databases, message queues, etc.) is performed in atomic ways, that is, all success or all fails. The working principle of the JTA framework is based on two key concepts: transaction manager and resource manager.The transaction manager is responsible for coordinating and managing affairs, and the resource manager is responsible for managing the transaction processing of specific resources. The working principle of the JTA framework will be introduced in detail below. 1. Registered transaction manager: In the Java application, you first need to register a transaction manager through the JTA framework.The transaction manager is responsible for coordinating and controlling the execution process of the entire distributed transaction. ```java TransactionManager tm = com.arjuna.ats.jta.TransactionManager.transactionManager(); ``` 2. Starting transaction: Once the transaction manager is registered successfully, you can start a new transaction by calling the `Begin` method. ```java tm.begin(); ``` 3. Get resource manager: Next, you need to obtain a resource manager who wants to participate in transactions.The resource manager can be a database connection, message queue, and so on. ```java DataSource DataSource = // Initialized data source XAResource xar = dataSource.getXAResource(); ``` 4. Registration resources: By calling the `Gettransaction 'method of the transaction manager, the resource manager is registered into the current transaction. ```java Transaction txn = tm.getTransaction(); txn.enlistResource(xar); ``` 5. Executive business logic: In affairs, you can perform various business logic and operations.The operations on all resource managers will be performed in the same transaction. ```java // Execute the database operation Connection conn = dataSource.getConnection(); // ... PreparedStatement pstmt = conn.prepareStatement("INSERT INTO table_name VALUES (?, ?)"); pstmt.setInt(1, value1); pstmt.setString(2, value2); pstmt.executeUpdate(); ``` 6. Submit or roll back transactions: Once all business logic is executed, you can choose to submit or roll the transaction. ```java // Submit a transaction tm.commit(); // or roll back transactions tm.rollback(); ``` The JTA framework has achieved the management and control of distributed transactions through registered transaction managers and resource managers, and uniformly coordinated the operation of multiple resources.Throughout the transaction, if any resource error or failure occurs, the JTA framework will roll back all operations to ensure the consistency and integrity of the data. It should be noted that when using the JTA framework, it is necessary to ensure that all the resources of participating transactions can provide the implementation of the XARESource interface to interact with the transaction manager. To sum up, the JTA framework is an important component for handling distributed transactions in the Java class library.Through the registration of the transaction manager, the acquisition and registration of resource manager, and the implementation of business logic, the JTA framework can ensure that the operation of multiple resources is performed by atomic.This provides convenient and powerful tools for the development of large -scale, distributed Java applications. I hope this article can help you understand the working principle of the "JTA" framework in the Java class library!

Analysis of the technical principles of the Play Services GCM framework in the Java class library Overview: Play Services GCM (Google Cloud Messaging) is a service framework provided by Google to pass messages between Android applications.When using the GCM framework in the Java library, following specific technical principles can help developers achieve more reliable, efficient and secure communication.This article will in -depth analysis of the technical principles of the Play Services GCM framework in the Java library and provide corresponding code examples. Technical principles analysis: 1. Use Google Play service library: In order to use the GCM framework, we must first ensure that the Google Play service library is correctly integrated.Use Gradle to build tools in the Android project, which can be introduced into the library by adding dependencies to the built.gradle file.The following is an example: ```java dependencies { implementation 'com.google.android.gms:play-services-gcm:17.0.0' } ``` 2. Configure Manifest file: The GCM framework needs to be configured in the manifest file of the application.The corresponding permission and service statement must be added, and the service category of the package name and processing the receiving message is specified.The following is an example: ```xml <manifest> <permission android:name="<your_package_name>.permission.C2D_MESSAGE" android:protectionLevel="signature" /> <uses-permission android:name="<your_package_name>.permission.C2D_MESSAGE" /> <application> <service android:name=".GcmMessageHandler" android:exported="false"> <intent-filter> <action android:name="com.google.android.c2dm.intent.RECEIVE" /> </intent-filter> </service> <receiver android:name=".GcmBroadcastReceiver" android:permission="com.google.android.c2dm.permission.SEND"> <intent-filter> <action android:name="com.google.android.c2dm.intent.REGISTRATION" /> <category android:name="<your_package_name>" /> </intent-filter> </receiver> </application> </manifest> ``` 3. Registration device: When the application starts, the registered device is required to obtain the unique device identifier.Developers can create a separate class, responsible for handling the logic of equipment registration, and call the register method provided by the GCM framework at appropriate.The following is an example: ```java public class GcmRegistrationUtil { // Define the name of the ACTION name for broadcast processing results public static final String REGISTRATION_COMPLETE = "registrationComplete"; // Register equipment public void registerDevice(Context context) { GoogleApiAvailability api = GoogleApiAvailability.getInstance(); int resultCode = api.isGooglePlayServicesAvailable(context); if (resultCode == ConnectionResult.SUCCESS) { Intent intent = new Intent(REGISTRATION_COMPLETE); String regId = FirebaseInstanceId.getInstance().getToken(); intent.putExtra("registrationId", regId); LocalBroadcastManager.getInstance(context).sendBroadcast(intent); } } } ``` 4. Receive and processing messages: In the application, receiving and processing GCM messages need to create a service class that inherits from GCMListenerService.Through the method of rewriting the class, developers can customize the receiving messages.The following is an example: ```java public class GcmMessageHandler extends GcmListenerService { @Override public void onMessageReceived(String from, Bundle data) { String message = data.getString("message"); // Customize the receiving message received // ... // Display notification to the notification column sendNotification(message); } private void sendNotification(String message) { // Construction notice NotificationCompat.Builder builder = new NotificationCompat.Builder(this) .setSmallIcon(R.drawable.notification_icon) .setContentTitle("GCM Notification") .setContentText(message) .setPriority(NotificationCompat.PRIORITY_DEFAULT) .setAutoCancel(true); // Display notification NotificationManagerCompat notificationManager = NotificationManagerCompat.from(this); notificationManager.notify(0, builder.build()); } } ``` in conclusion: This article detailed the technical principles of using the Play Services GCM framework in the Java library and provided the corresponding code example.By following these principles, developers can implement reliable, efficient and secure message transmission functions in Android applications.

How to use the OSGI service condition to implement the automatic assembly of the Java library In the development of Java, sometimes it is necessary to automatically assemble different class libraries into the application.In this case, we can use the OSGI service conditions to achieve automatic assembly.OSGI is a service -oriented modular architecture. It provides a dynamic modular system that allows developers to split the application into different modules. They can be installed, started, stopped and updated independently. At the same time, they can cooperate with each other.Essence step: 1. Define the service interface: First of all, we need to define a service interface, which defines a set of methods for operation and query.For example, we can create an interface called MessageService, which contains a SendMessage method. The example code is as follows: ```java public interface MessageService { void sendMessage(String message); } ``` 2. Implement service interface: Then, we need to create a class that implements the service interface.These classes will provide specific implementation logic. The example code is as follows: ```java public class EmailService implements MessageService { public void sendMessage(String message) { // Send email logic } } public class SMSService implements MessageService { public void sendMessage(String message) { // Send SMS logic } } ``` 3. Creating OSGI Bundle: Next, we need to pack the service for OSGI Bundle.In this Bundle's manifest.mf, we need to declare the relationship between the service interface and the implementation class. Example manifest.mf file is as follows: ``` Bundle-SymbolicName: com.example.message Export-Package: com.example.message Service-Component: OSGI-INF/*.xml ``` 4. Create a component description file: In OSGI Bundle, we also need to create a component description file to illustrate the relationship between the service interface and the implementation class. Example component description file (Osgi-inf/com.example.Message.MessageSageservice.xml) Content is as follows: ```xml <?xml version="1.0" encoding="UTF-8"?> <scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.3.0" name="com.example.message"> <implementation class="com.example.message.EmailService"/> <service> <provide interface="com.example.message.MessageService"/> </service> </scr:component> ``` 5. Configure OSGI container: Now, we need to deploy the OSGI Bundle to the OSGI container.According to different OSGI containers, deployment methods may be different. 6. Automatic assembly service: In applications, you can get OSGI services by dynamically obtaining OSGI services.We can use the ServiceTracker class provided by OSGI to achieve this purpose. The example code is as follows: ```java import org.osgi.framework.BundleContext; import org.osgi.framework.InvalidSyntaxException; import org.osgi.framework.ServiceReference; import org.osgi.util.tracker.ServiceTracker; public class Application { private ServiceTracker<MessageService, MessageService> messageServiceTracker; public void start(BundleContext context) { try { String filter = "(objectClass=" + MessageService.class.getName() + ")"; messageServiceTracker = new ServiceTracker<>(context, context.createFilter(filter), null); messageServiceTracker.open(); } catch (InvalidSyntaxException e) { e.printStackTrace(); } } public void stop(BundleContext context) { messageServiceTracker.close(); messageServiceTracker = null; } public void sendMessage(String message) { MessageService messageService = messageServiceTracker.getService(); if (messageService != null) { messageService.sendMessage(message); } else { // The situation where the processing service is not found } } } ``` Summarize: The use of OSGI service conditions to achieve automatic assembly of the Java library can effectively reduce code coupling and improve the scalability and maintenance of the code.By defining the service interface and implementation class, and packing them into OSGI Bundle, the OSGI service is automatically assembled by dynamically obtaining OSGI services in the application. We can easily switch the service when needed. I hope that this article can help you understand how to use the OSGI service conditions to realize the automatic assembly of the Java library.

UJO ORM framework and its technical principles in the Java class library analysis In Java application development, ORM (object relationship mapping) is a common technology. It combines relational databases with object -oriented programming language, so that developers can operate databases in an object -oriented manner.The UJO ORM framework is an important Java class library that provides a powerful ORM function. This article will analyze the technical principles of the UJO ORM framework. 1. Overview of UJO ORM Framework The UJO ORM framework is an ORM tool based on the Java reflection mechanism and annotation. It is encapsulated on the basis of the JDBC (Java database connection) to simplify the interactive operation with the database.The UJO ORM framework provides easy -to -use APIs, allowing developers to quickly perform database operations while maintaining good maintenance and scalability. Second, the core principle of the UJO ORM framework 1. The mapping of the physical class The UJO ORM framework maps the Java entity class and the table in the database by annotation.Developers can use @Entity annotations to identify a class as a physical class, and use the @Table annotation to specify the corresponding relationship between the physical class and the database table.In addition, @Column annotations can be used to specify the mapping relationship between the attributes in the physical class and the field in the database table. The example code is as follows: ```java @Entity @Table(name = "user") public class User { @Id @Column(name = "id") private int id; @Column(name = "username") private String username; // getter and setter methods } ``` 2. Database operation installation The UJO ORM framework encapsulates common database operations, such as adding, deletion, modification, etc., so that developers can call database operations through simple APIs.Developers can use the EntityManager class to manage the physical class. Through this method, they can create, update, delete physical objects, and perform query operations. The example code is as follows: ```java // Create EntityManager object EntityManager entityManager = new EntityManager(); // Create physical objects User user = new User(); user.setId(1); user.setUsername("John"); // Insert the entity object entityManager.persist(user); // Update the physical object user.setUsername("John Smith"); entityManager.update(user); // Delete the physical object entityManager.remove(user); // Query physical object User retrievedUser = entityManager.find(User.class, 1); ``` 3. Affairs management The UJO ORM framework also provides the function of transaction management. Developers can use annotations to identify methods that need to be managed.By adding @transactional annotations to the method, the UJO ORM framework will automatically manage this method to ensure the consistency and integrity of the data. The example code is as follows: ```java @Transactional public void updateUser(User user) { // Update user information entityManager.update(user); // Update other related operations // ... } ``` Third, the advantage of the UJO ORM framework 1. Simplify database operation: The UJO ORM framework encapsulates common database operations, simplifies the interaction with the database, and developers do not need to write tedious SQL statements. 2. Improve development efficiency: The UJO ORM framework provides easy -to -use APIs. Developers can quickly perform database operations to improve development efficiency. 3. Provide transaction management: UJO ORM framework supports transaction management, ensuring the consistency and integrity of data. 4. Strong expansion: The UJO ORM framework is based on the Java reflection mechanism and annotation. It has good expansion. Developers can customize the annotation and expansion framework function. In summary, the UJO ORM framework is a powerful Java class library that provides simplified database operation and reliable transaction management functions, enabling developers to develop database development more efficiently.

Analysis of the core characteristics of the "Affairs JTA" framework in the Java class library Overview: The Java transaction API (JTA) is a standard interface for managing distributed transactions.It provides a mechanism to coordinate the transaction processing of multiple resources (such as databases, message queues, etc.) to ensure that they succeed or fail at the same time.This article will analyze the core features of the "Anti -Affairs JTA" framework in the Java library, and provide some Java code examples to explain. 1. Atomicity: Affairs is an atomic operation unit, either successfully executed or all failed.The JTA framework uses Two-Phase Commit (2PC) to achieve atomicity.The following is an example of code using the JTA framework: ``` import javax.transaction.*; import javax.naming.*; public class TransactionExample { public static void main(String[] args) throws Exception { UserTransaction transaction = (UserTransaction) new InitialContext().lookup("java:comp/UserTransaction"); try { transaction.begin(); // Execute the operation related to transactions // Submit a transaction transaction.commit(); } catch (Exception e) { // Roll back transactions transaction.rollback(); e.printStackTrace(); } } } ``` 2. consistency (consistency): The consistency requires that the data in the database before and after the execution of the transaction must be consistent.The JTA framework supports the operation of the operation of multiple data sources (such as multiple databases) in a distributed transaction.If one of the data sources fails the transaction failure, all other data sources will roll back to the state before the start of the transaction. 3. Isolation: The isolation of transactions requires that each transaction should be isolated when performing concurrent execution and does not interfere with each other.The JTA framework provides configurable isolation levels, such as Read Uncommitted, Read Community, Repeating (Repeatable Read), and Serializable.The following is an example of setting the isolation level: ``` import javax.transaction.*; import javax.naming.*; public class TransactionExample { public static void main(String[] args) throws Exception { UserTransaction transaction = (UserTransaction) new InitialContext().lookup("java:comp/UserTransaction"); try { // Set the isolation level as the repeated readable transaction.setTransactionIsolation(Connection.TRANSACTION_REPEATABLE_READ); transaction.begin(); // Execute the operation related to transactions // Submit a transaction transaction.commit(); } catch (Exception e) { // Roll back transactions transaction.rollback(); e.printStackTrace(); } } } ``` 4. Durability: When the transaction is successfully submitted, the result should be permanently preserved in the persistent storage medium, and it will not be lost even if the system failure occurs.This requires the use of the JTA framework to interact with the reliable persistent storage medium (such as database) to ensure the durability of the transaction. Summarize: The JTA framework provides a simple and powerful tool for Java developers to handle distributed transactions.Its core characteristics include atomic, consistency, isolation and durability.Through reasonable use of the JTA framework, developers can ensure that the transaction processing of multiple resources is successful or failed at the same time to ensure the consistency and reliability of the system data. Please note that the Java code example provided herein is only used to explain the purpose. Under actual situation, appropriate modification and adjustment may be required according to specific requirements.

Jimmutable Collections is a set of tools in the Java class library to build persistent and efficient inseparable sets.In this article, we will explore the principles, uses, and sample code of Jimmutable Collections. The variable sets in Java (such as ArrayList and HashMap) allows modification during use, which may cause errors and inconsistency.The uncharacteristic collection refers to a collection that cannot be modified once it is created. This characteristic is particularly useful in concurrent environment. Jimmutable Collections achieves non -variability by using persistent data structures.The durable data structure means that when modifying, the original structure will not be modified, but to create a new structure and share as many common data as possible.This method of sharing makes Jimmutable Collections very efficient when a large amount of data modification. Jimmutable Collections supports a variety of data structures, including List, MAP and SET.Below we will show how to use Jimmutable Collections to build uncharacteristic sets through some example code. First of all, let's create an inseparable list: ```java JImmutableList<String> list = JImmutables.listOf("apple", "banana", "cherry"); System.out.println (list); // Output: ["Apple", "Banana", "Cherry"] // Add elements to the list JImmutableList<String> newList = list.insert("date"); System.out.println (newList); // Output: ["Apple", "Banana", "Cherry", "Date"] // Delete elements from list JImmutableList<String> newerList = newList.delete("banana"); System.out.println (NEWERLIST); // Output: ["Apple", "Cherry", "Date"] ``` By calling the method of `jimmutables.listof (), we can create a variable list.We can use the `Insert ()" method to add elements to the list, and use the `delete () method to delete the element from the list.It should be noted that each modification operation will return a new list, and the original list will not be modified. Next, let's take a look at how to create an immutable map: ```java JImmutableMap<String, Integer> map = JImmutables.mapOf("apple", 1, "banana", 2, "cherry", 3); System.out.println (map); // Output: {"apple" = 1, "banana" = 2, "cherry" = 3} // Add key values to the map JImmutableMap<String, Integer> newMap = map.assign("date", 4); System.out.println (newmap); // Output: {"apple" = 1, "banana" = 2, "cherry" = 3, "date" = 4} // Delete the key value pair from the map JImmutableMap<String, Integer> newerMap = newMap.delete("banana"); System.out.println (newsmap); // Output: {"Apple" = 1, "Cherry" = 3, "Date" = 4} ``` Similar to creating List, we can use `jimmutables.mapof ()` method to create a variable MAP.Use the `Assign ()" method to add key value pairs to the map, and use the `delete () method to delete the key value from the map.Similarly, each modification operation returns a new MAP, and the original Map will not be modified. In addition to List and Map, Jimmutable Collections also supports other data structures, such as SET.Use a similar way to use the method of `jimmutables.setof ()` to create a non -variable set, and modify the set using the methods such as `Insert (),` Delete () `. In summary, Jimmutable Collections is a tool used in the Java library to build a tool for persistent and efficient and uncharacteria.By using persistent data structure and sharing data, Jimmutable Collections can provide efficient collection operations and thread security.Whether in a concurrent environment, or in the scene where the collection is needed frequently, Jimmutable Collections is a very useful tool. I hope this article can help you understand and use Jimmutable Collections!

Kotlinpote is a code generating framework for Kotlin language.It provides a simple, powerful and easy -to -use API, which can help developers generate Kotlin source code by programming.This article will introduce the basic concepts and uses of the KotlinpoET framework, and provide some Java code examples. 1. Basic concept 1.1 Type (Type) In Kotlinpoet, the type refers to the data types in Kotlin, such as int and string.You can create a type through the TypeSpec class, and set its name, modification, attributes, methods, constructors, etc. 1.2 Function (Function) The function is used to perform specific operations or calculations.Kotlinpock provides a FunSpec class to create functions, and the name, modifier, parameter, return type of function can be set. 1.3 Property The attribute is a member variable in the class that is used to store the state of the object.The PropertySpec class in Kotlinpock can be used to create attributes, and can set the name, modification symbol, type, initialization value of the attribute. 1.4 Constructor (Constructionor) The constructor is used to create objects and initialize.Kotlinpoet's ConstructorSpec class can be used to create a constructive function, and the modifier and parameters of the constructor can be set. 1.5 package (Package) KotlinPOET supports creation -level code.The name of the package can be defined by the PackageSpec class, and the type, function, etc. can be added to the package. 1.6 File (File) In Kotlin, the source code is organized in the form of files.Kotlinpoet's FileSpec class is used to create source code files, and the package name of the file can be set, and the imported class. Second, use 2.1 Generate java code Through Kotlinpoet, developers can generate Java code by programming.For example, you can use KOTLINPOET to create Java class, interfaces, enumerations, etc., and set member variables, methods, constructors, etc. of the class. Below is an example code that generates the Java class using KotlinPOET: ```java File file = new File("path/to/GeneratedClass.java"); TypeName superclassName = ClassName.get("com.example", "Superclass"); TypeSpec generatedClass = TypeSpec.classBuilder("GeneratedClass") .superclass(superclassName) .addModifiers(Modifier.PUBLIC) .build(); JavaFile javaFile = JavaFile.builder("com.example", generatedClass) .build(); javaFile.writeTo(file); ``` The above code uses KotlinPOET to create a Java class called "GenetEdClass", and set its parent class as "SuperClass", and the modifier is PUBLIC.Write the generated code into the specified file with JavaFile. 2.2 Automatically generate code With the help of Kotlinpoet, developers can automatically generate code according to specific rules or templates.For example, the corresponding data model class can be generated according to the database table structure. The following is an example code that automatically generates the data model class based on the database table structure of KotlinPOET: ```java List<TableMetaData> tableMetaDataList = fetchTableMetaDataFromDatabase(); for (TableMetaData tableMetaData : tableMetaDataList) { String className = capitalize(tableMetaData.getTableName()); TypeSpec dataModelClass = TypeSpec.classBuilder(className) .addModifiers(Modifier.PUBLIC) .addProperties(generateProperties(tableMetaData)) .addMethods(generateGettersAndSetters(tableMetaData)) .build(); JavaFile javaFile = JavaFile.builder("com.example.model", dataModelClass) .build(); javaFile.writeTo(file); } ``` The above code obtains the metadata from the database, and generates the corresponding data model class according to the information of each table.By looping to the metadata list, the attributes and methods of generating class are used using the Kotlinpoet, and the generated code is written into the specified file. in conclusion: Kotlinpote is a powerful Kotlin code generating framework that can help developers generate Kotlin source code by programming.It provides a simple and easy -to -use API to make code generation more efficient and flexible.Whether it is generating a Java code or automatic generating code, KotlinPOET can provide developers with convenient solutions.