The activity of the Java library in the Kotlin framework is expanded in detail

Detailed explanation of the activity of the Java library in the Kotlin framework introduction: Kotlin is a static type programming language running on the Java virtual machine. It is closely integrated with the Java language and can interact seamlessly with the Java library.In Kotlin, the characteristics and functions of the Java class library can be used directly, and the function of the Java class library can also be expanded through activity expansion to achieve more flexible and efficient development. Event expansion is a unique feature of the Kotlin language. It allows developers to add new member functions and attributes to the existing class without modifying the original Java class.In this way, we can add some custom functions to the Java class library through activity, while maintaining compatibility with the original Java class library. The syntax of the event extension is shown below: fun ClassName.functionName() { // function body } Activity extension can add new functions to any class.In the Java library, a common case is to add new functions to the String class of the Java.The following is an example code that demonstrates how to expand through the activity to add a new function to the String class of the Java in Kotlin: kotlin fun String.isPalindrome(): Boolean { val reversed = this.reversed() return this == reversed } In the above code, we have added an iSpalindrome () function to the String class to determine whether a string is a reply.Using this function, we can easily check whether a string is a replied without modifying the original Java library. In addition to functions, we can also use activity to expand new attributes.The following is an example code that demonstrates how to add a new attribute to the File class of the Java to obtain the size of the file: kotlin val File.fileSize: Long get() = length() In the above code, we have added a Filesize property to the File class to obtain the size of the file.In this way, we can easily obtain the size of the file without modifying the original Java library. It should be noted that the event extension does not truly modify the source code of the Java library, but converts the extension and attributes into static methods and static fields during compilation.This means that event expansion will not affect the existing Java code, and it will not be visible in the Java language. Summarize: Through activity expansion, we can add new functions and properties to the Java library in the Kotlin framework to expand its functions.The event extension can be seamlessly integrated with the Java library, maintaining the simplicity and readability of the code.By mastering the use of activity extensions, we can better use the characteristics of KOTLIN to improve development efficiency. I hope this article will help you understand the expansion of the Java library in the Kotlin framework.thanks for reading! (Translation:) Title: Detailed Explanation of Active Extensions in Kotlin Framework for Java Libraries Introduction: Kotlin is a statically-typed programming language that runs on the Java Virtual Machine (JVM). It integrates closely with the Java language, allowing seamless interaction with Java libraries. In Kotlin, you can directly utilize the features and functionalities of Java libraries, and also extend their capabilities through active extensions, enabling more flexible and efficient development. Active extensions are a unique feature of the Kotlin language that allows developers to add new member functions and properties to existing classes without modifying the original Java classes. This way, we can extend the functionality of Java libraries with custom features while maintaining compatibility with the original Java libraries. The syntax of active extensions is as follows: fun ClassName.functionName() { // Function body } Active extensions can be added to any class. A common use case in Java libraries is to add new functions to the Java String class in Kotlin. Here's an example code demonstrating how to add a new function to the Java String class in Kotlin using an active extension: kotlin fun String.isPalindrome(): Boolean { val reversed = this.reversed() return this == reversed } In the above code, we added an isPalindrome() function to the String class, which checks whether a string is a palindrome. With this function, we can conveniently check whether a string is a palindrome without modifying the original Java library. In addition to functions, we can also use active extensions to add new properties. Here's an example code demonstrating how to add a new property to the Java File class in Kotlin to retrieve the size of the file: kotlin val File.fileSize: Long get() = length() In the above code, we added a fileSize property to the File class, which retrieves the size of the file. Through this approach, we can easily retrieve the size of a file without modifying the original Java library. It's important to note that active extensions do not actually modify the source code of Java libraries. Instead, during compilation, the extension functions and properties are converted into static methods and fields. This means that active extensions do not impact existing Java code and are not visible in the Java language. Summary: Through active extensions, we can extend the functionality of Java libraries in Kotlin by adding new functions and properties. Active extensions seamlessly integrate with Java libraries, preserving code simplicity and readability. By mastering the usage of active extensions, we can better leverage the features of Kotlin and improve development efficiency. We hope this article helps you understand the active extensions in Kotlin framework for Java libraries. Thank you for reading!