Kotlin 简明教程

Kotlin - Environment Setup

Installing Kotlin command-line compiler

Kotlin 的一个主要特性是它与 Java 具有互操作性，这意味着您可以在同一应用程序中编写 Kotlin 和 Java 代码。与 Java 一样，Kotlin 也在 JVM 上运行，因此要直接在 Windows 上安装 Kotlin 并使用命令行进行操作，您需要确保系统中已安装 JDK。

One of the key features of Kotlin is that it has interoperability with Java i.e. You can write Kotlin and Java code in the same application. Like Java, Kotlin also runs on JVM therefore to install Kotlin on Windows directly and work with it using the command line You need to make sure you have JDK installed in your system.

Verifying the Java installation

若要验证 Java 安装，请执行以下操作：

To verify Java installation −

Open command prompt and verify the current version of Java using the javac version command −

C:\Users\TP>javac -version
javac 1.8.0_261

如果您尚未在系统中安装 Java，它将生成以下错误：

If you doesn’t have Java installed in your system it generates the following error

C:\Users\Krishna Kasyap>javac -v
'javac' is not recognized as an internal or external command,
operable program or batch file.

您可以按照以下步骤安装 JDK：

You can install JDK by following the steps given below

Installing JDK8

Open the following Oracle Java Downloads page.
Click on the JDK Download link under Java SE 8 section.

This will redirect to the page that contains JDK software for various platforms, select the desired version (.exe) and download it.

After downloading the file JDK file (assume we have downloaded jdk_windows-x64_bin.exe), start the installation by running it.

By default, Java will be installed in the path C:\Program Files\Java\jdk1.8.0_301\ you can change the path by clicking on the Change… button.

After the completion of the installation click on the Close button.

Kotlin Command line compiler

Kotlin 命令行编译器可在 JetBrains Kotlin GitHub releases page 中获得。

Kotlin command line compiler is available at the JetBrains Kotlin GitHub releases page.

Download the latest version.
Unzip the downloaded file and place it in the desired folder.
The Bin directory of the downloaded folder contains all the binary files to run Kotlin.

Now, set Path environment variable to this folder.

Setting the Path variable

Right click on My computer or This PC, select Properties.

Click on Advanced System Settings.

Then, click on the Environment Variables… button.

In the Environment Variables window, under System Variables select the Path variable and edit the variables using the Edit… button.

Click on the New button and add the path of the bin folder of installed JDK and Kotlin folders.

要验证安装，请打开命令提示符并键入 java 或 javac 命令，如果安装成功，则可以看到如下所示的输出：

To verify the installation, open command prompt and type java or javac command, if your installation is successful, you can see the output as shown below:

Setting Kotlin environment using IntelliJ IDEA

Kotlin 由 JetBrains 开发，它开发了像 AppCode、CLion、DataGrip、DataSpell、GoLand、IntelliJ IDEA 等 IDE。

Kotlin is developed by the JetBrains that develops IDEs like AppCode, CLion, DataGrip, DataSpell, GoLand, IntelliJ IDEA etc.

IntelliJ IDEA 内部捆绑了 Kotlin 插件。要开发 Kotlin，请下载并安装 IntelliJ。

The IntelliJ IDEA internally have Kotlin plugin bundled with it. To develop Kotlin download and install IntelliJ.

要安装最新版本的 IntelliJ IDEA：

To install a recent version of IntelliJ IDEA:

Open JetBrains Downloads page, you can download the free community edition.

If you run the downloaded file, it starts the installation process.

Proceed with the installation by providing the required details and finally complete the installation.

The Plugins tab of IntelliJ displays all the available plugins. By default, Kotlin plugin is activated, in any case if it is not activated. Open the plugin tab, search for Kotlin and install it.

Creating first application

To create first application, click on NewProject.

Select Kotlin/JVM and click Next.

Name the project and select the desired location.

Now, create a new Kotlin file under the source(src) folder and let’s name it as Test.

You can create a sample function as shown below. You can run this by pressing Ctrl + Shift + F10.

Setting Kotlin environment using Eclipse

您还可以在 eclipse 中执行 Kotlin 程序，为此，您需要在系统中安装 “Eclipse IDE for Java developers” 。要进行操作，请按以下步骤操作。

You can also execute Kotlin programs in eclipse to do so, you need to have “Eclipse IDE for Java developers” installed in your system. To do so, follow the steps given below.

Download the latest version of eclipse installer from the page: https://www.eclipse.org/downloads/

Run the downloaded file and click on the Eclipse IDE for Java developers.

Select the installation directory and click on install.

Open eclipse in the Help menu select Eclipse Marketplace.

Search for Kotlin and check all the matches and when you find Kotlin click on Install.

Creating a Kotlin application in eclipse

在 Eclipse 中安装 Kotlin 插件后，即可创建第一个应用程序。

Once you have installed Kotlin plugin in your eclipse to create your first application.

In the File menu click on Project.

This will take you to Select a wizard. Under Kotlin (dropdown menu), click on select “Kotlin Project” and click on the “Next” button.

Then, enter the desired name for the application and click on Next.

Right click on the src folder of the created project click on other.

Select the Kotlin File wizard click on Next and name the file as Hello.kt.

你的开发环境现在已经准备就绪。继续在 “Hello.kt” 文件中添加以下代码片段。

Your development environment is ready now. Go ahead and add the following piece of code in the “Hello.kt” file.

fun main(args: Array) {
   println("Hello, World!")
}

将它作为 Kotlin 应用程序运行，并在控制台中查看输出，如下面的屏幕截图所示。为了更好的理解和可用性，我们将使用我们的编码地工具。

Run it as a Kotlin application and see the output in the console as shown in the following screenshot. For better understanding and availability, we will be using our coding ground tool.