ZIO CLI Framework: The Best Practice for Building a Custom Command Line Interface Using Java Class Libraries

ZIO CLI Framework: Best Practices for Building Custom Command Line Interfaces Using Java Class Libraries Overview: Command line interface (CLI) is an important component of many applications. They provide a simple and powerful way to interact with applications, allowing users to perform various operations by entering commands. It is a common practice in Java development to use Java class libraries to build custom command-line interfaces. This article will introduce the ZIO CLI framework, which is a powerful and easy-to-use Java class library that can help us quickly build custom command-line interfaces. Introduction to ZIO CLI: ZIO CLI is a command line interface framework built on the ZIO library. ZIO is a Scala library based on pure functional programming, providing a powerful way to handle asynchronous and concurrent operations. By combining the ZIO CLI framework, we can easily write command line applications with complex logic and interactivity. Features of ZIO CLI: 1. Commands and subcommands: The ZIO CLI framework allows us to define multiple commands and subcommands, and define corresponding parameters and options for each command. 2. Parameter parsing: The ZIO CLI framework provides powerful parameter parsing functionality, allowing us to define different types of parameters and specify their constraints and default values. 3. Option parsing: The ZIO CLI framework allows us to define various options and specify different types and default values for each option. 4. Command Execution: By using ZIO Tasks, we can define the execution logic of commands. ZIO tasks are pure functions that can handle asynchronous and concurrent operations while providing reliable error handling mechanisms. 5. Automatic help generation: The ZIO CLI framework provides the function of automatically generating help documents. We can specify the description information of commands and parameters through simple code annotations, and then automatically generate a complete help document. Examples of using ZIO CLI: Below is a simple example of using the ZIO CLI framework to build a command line interface to help you better understand its usage. import zio.duration._ import zio.{App, ZIO} import zio.cli._ import zio.console._ object MyCLI extends Command[String, Unit] { val name = "mycli" val description = "A simple CLI example" val command = (option[String](List("name"), description = "Your name") <&> option[Int](List("times"), description = "Number of times to greet", default = Some(1))).to[MyCommand] def run(args: String, command: MyCommand): ZIO[Console, Nothing, Unit] = putStrLn(s"Greetings, ${command.name}!") *> ZIO.foreach(0 until command.times)(_ => putStrLn("Hello!")).unit } case class MyCommand(name: String, times: Int) object Main extends App { def run(args: List[String]): ZIO[ZEnv, Nothing, Int] = MyCLI.execute(args.mkString(" ")).fold( err => putStrLn(s"Execution failed with: $err") *> ZIO.succeed(1), _ => ZIO.succeed(0) ) } In the above example, we defined a command-line application called "MyCLI". It has only one command and accepts a "name" parameter and a "times" option. In the run method, we use ZIO tasks to execute the logic of the command. In the Main object, we ran this application. Through this example, you can see that using the ZIO CLI framework is very simple and intuitive. It provides an elegant way to define command line interfaces and separate business logic from user interaction. Conclusion: The ZIO CLI framework provides Java developers with a powerful and easy-to-use tool for building custom command-line interfaces. It makes the development of command line applications simpler and more reliable by combining the functions of the ZIO library. If you are developing a command-line application, you may want to try the ZIO CLI framework, which will bring you a pleasant development experience.