Java 9 引進了一個新的互動式工具,稱為JShell。此工具可用於執行表達式、類別、介面、枚舉等。
詳細的文檔可以在 JShell 中找到,其中包含完整信息,以及使用其內部命令和各種選項的信息。可以使用兩個命令存取此文件:「/help」和「/?」。 JShell的文檔不僅限於其內部控制的訊息,還包括Javadoc。
在下面的程式碼片段中,可以透過使用「 /help」指令。
<strong>jshell> /help | Type a Java language expression, statement, or declaration. | Or type one of the following commands: | /list [<name or id>|-all|-start] | list the source you have typed | /edit <name or id> | edit a source entry referenced by name or id | /drop <name or id> | delete a source entry referenced by name or id | /save [-all|-history|-start] <file> | Save snippet source to a file. | /open <file> | open a file as source input | /vars [<name or id>|-all|-start] | list the declared variables and their values | /methods [<name or id>|-all|-start] | list the declared methods and their signatures | /types [<names or id>|-all|-start] | list the declared types | /imports | list the imported items | /exit | exit jshell | /env [-class-path <path> ] [-module-path <path>] [-add-modules <modules>] ... | view or change the evaluation context | /reset [-class-path <path>] [-module-path <path>] [-add-modules <modules>]... | reset jshell | /reload [-restore] [-quiet] [-class-path <path>] [-module-path <path>]... | reset and replay relevant history -- current or previous (-restore) | /history | history of what you have typed | /help [<command>|<subject>] | get information about jshell | /set editor|start|feedback|mode|prompt|truncation|format ... | set jshell configuration information | /? [<command>|<subject> ] | get information about jshell | /! | re-run last snippet | / | re-run snippet by id | /- | re-run n-th previous snippet | For more information type '/help' followed by the name of a command or a subject. | For example '/help /list' or '/help intro'. | | Subjects: | | intro | an introduction to the jshell tool | shortcuts | a description of keystrokes for snippet and command completion, | information access, and automatic code generation | context | the evaluation context options for /env /reload and /reset</strong>
JShell 列印不同的現有內部命令,並快速介紹它們的用途,並存取其使用的更詳細說明。為此,我們只需輸入命令:“/help”,然後輸入詳細的命令名稱(例如“/set”命令)。 < /p>
<strong>jshell> /help /set | | /set | | Set jshell configuration information, including: | the external editor to use, the start-up definitions to use, a new feedback mode, | the command prompt, the feedback mode to use, or the format of output. | | /set editor [-wait] ... | Specify the command to launch for the /edit command. | The <command> is an operating system dependent string. | | /set start <file> | The contents of the specified become the default start-up snippet s and commands. | | /set feedback <mode> | Set the feedback mode describing displayed feedback for entered snippets and commands. | | /set mode <mode>[<old-mode>] -command|-quiet|-delete | Create or update a user-defined feedback mode, optionally copying from an existing mode. | | /set prompt <mode>"<prompt>" "<continuation-prompt>" | Set the displayed prompts for a given feedback mode. | | /set truncation <mode> <length> <selector> ... | Set the maximum length of a displayed value. | | /set format <mode> <field> "<format>" ... | Configure a feedback mode by setting the format of a field when the selector matches. | | /set | Show editor, start, and feedback settings as /set commands. | To show the settings of any of the above, omit the set value. | | To get more information about one of these forms, use /help with the form specified. | For example: /help /set format</strong>
我們需要找到第三部分輸入的命令,是否修改JShell的回傳(/set Feedback),以修改預設編輯器(/set editor),或修改JShell的啟動(/set start)。
<strong>jshell> /help /set feedback | Set the feedback mode describing displayed feedback for entered snippets and commands: | | /set feedback [-retain] <mode> | | Retain the current feedback mode for future sessions: | | /set feedback -retain | | Show the feedback mode and list available modes: | | /set feedback | | Where <mode> is the name of a previously defined feedback mode. | You may use just enough letters to make it unique. | User-defined modes can be added, see '/help /set mode' | | When the -retain option is used, the setting will be used in this and future | runs of the jshell tool. | | The form without <mode> or -retain displays the current feedback mode and available modes.</strong>
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