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Java 9中的JShell?

王林   2023-09-17 11:25   978浏览 转载

java 9中的jshell?

JShell是 Java 9 版本中引入的新概念。它为 Java 提供了REPL(Read-Eval-Print-Loop)能力。通过使用 JShell,我们可以测试基于 Java 的逻辑表达式,而无需编译它。 REPL 充当即时反馈循环,对特定语言的生产力有很大影响。

第 1 步:打开命令提示符并输入 JShell

<strong>Microsoft Windows [Version 6.3.9600]
(c) 2013 Microsoft Corporation. All rights reserved.

C:\Users\User>JShell
| Welcome to JShell -- Version 9.0.4
| For an introduction type: /help intro

jshell></strong>

第 2 步:JShell 命令窗口开始运行后,键入 /help(以查看 JShell 命令)。

<strong>jshell> /help
| Type a Java language expression, statement, or declaration.
| Or type one of the following commands:
| /list [|-all|-start]
| list the source you have typed
| /edit
| edit a source entry referenced by name or id
| /drop
| delete a source entry referenced by name or id
| /save [-all|-history|-start]
| Save snippet source to a file.
| /open
| open a file as source input
| /vars [|-all|-start]
| list the declared variables and their values
| /methods [|-all|-start]
| list the declared methods and their signatures
| /types [|-all|-start]
| list the declared types
| /imports
| list the imported items
| /exit
| exit jshell
| /env [-class-path ] [-module-path ] [-add-modules </strong>

第三步:在JShell命令窗口中输入 /imports,获取JShell导入的包。

<strong>jshell> /imports
| import java.io.*
| import java.math.*
| import java.net.*
| import java.nio.file.*
| import java.util.*
| import java.util.concurrent.*
| import java.util.function.*
| import java.util.prefs.*
| import java.util.regex.*
| import java.util.stream.*</strong>

第 4 步:在 JShell 中执行计算(尝试使用 JShell 进行算术计算

<strong>jshell> 3+5
$1 ==> 8

jshell> 8-4
$2 ==> 4

jshell> 2*6
$3 ==> 12

jshell> 9%3
$4 ==> 0

jshell> 8/2
$5 ==> 4</strong>

第 5 步:要退出 JShell,请输入 /exit

<strong>jshell> /exit
| Goodbye</strong>

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