.\"t+
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.\" Copyright (c) 1994, 2019, Oracle and/or its affiliates. All rights reserved.+
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.\" DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.+
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.\" This code is free software; you can redistribute it and/or modify it+
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.\" under the terms of the GNU General Public License version 2 only, as+
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.\" published by the Free Software Foundation.+
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.\" This code is distributed in the hope that it will be useful, but WITHOUT+
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.\" ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or+
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.\" FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License+
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.\" version 2 for more details (a copy is included in the LICENSE file that+
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.\" accompanied this code).+
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.\" You should have received a copy of the GNU General Public License version+
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.\" 2 along with this work; if not, write to the Free Software Foundation,+
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.\" Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.+
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.\" Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA+
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.\" or visit www.oracle.com if you need additional information or have any+
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.\" questions.+
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.\"+
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.\" Automatically generated by Pandoc 2.3.1+
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.\"+
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.TH "JSHELL" "1" "2018" "JDK 13" "JDK Commands"+
−
.hy+
−
.SH NAME+
−
.PP+
−
jshell \- interactively evaluate declarations, statements, and+
−
expressions of the Java programming language in a read\-eval\-print loop+
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(REPL)+
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.SH SYNOPSIS+
−
.PP+
−
\f[CB]jshell\f[R] [\f[I]options\f[R]] [\f[I]load\-files\f[R]]+
−
.TP+
−
.B \f[I]options\f[R]+
−
Command\-line options, separated by spaces.+
−
See \f[B]Options for jshell\f[R].+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[I]load\-files\f[R]+
−
One or more scripts to run when the tool is started.+
−
Scripts can contain any valid code snippets or JShell commands.+
−
.RS+
−
.PP+
−
The script can be a local file or one of following predefined scripts:+
−
.TP+
−
.B \f[CB]DEFAULT\f[R]+
−
Loads the default entries, which are commonly used as imports.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]JAVASE\f[R]+
−
Imports all Java SE packages.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]PRINTING\f[R]+
−
Defines \f[CB]print\f[R], \f[CB]println\f[R], and \f[CB]printf\f[R] as+
−
\f[CB]jshell\f[R] methods for use within the tool.+
−
.RS+
−
.RE+
−
.PP+
−
For more than one script, use a space to separate the names.+
−
Scripts are run in the order in which they\[aq]re entered on the command+
−
line.+
−
Command\-line scripts are run after startup scripts.+
−
To run a script after JShell is started, use the \f[CB]/open\f[R] command.+
−
.PP+
−
To accept input from standard input and suppress the interactive I/O,+
−
enter a hyphen (\-) for \f[I]load\-files\f[R].+
−
This option enables the use of the \f[CB]jshell\f[R] tool in pipe chains.+
−
.RE+
−
.SH DESCRIPTION+
−
.PP+
−
JShell provides a way to interactively evaluate declarations,+
−
statements, and expressions of the Java programming language, making it+
−
easier to learn the language, explore unfamiliar code and APIs, and+
−
prototype complex code.+
−
Java statements, variable definitions, method definitions, class+
−
definitions, import statements, and expressions are accepted.+
−
The bits of code entered are called snippets.+
−
.PP+
−
As snippets are entered, they\[aq]re evaluated, and feedback is+
−
provided.+
−
Feedback varies from the results and explanations of actions to nothing,+
−
depending on the snippet entered and the feedback mode chosen.+
−
Errors are described regardless of the feedback mode.+
−
Start with the verbose mode to get the most feedback while learning the+
−
tool.+
−
.PP+
−
Command\-line options are available for configuring the initial+
−
environment when JShell is started.+
−
Within JShell, commands are available for modifying the environment as+
−
needed.+
−
.PP+
−
Existing snippets can be loaded from a file to initialize a JShell+
−
session, or at any time within a session.+
−
Snippets can be modified within the session to try out different+
−
variations and make corrections.+
−
To keep snippets for later use, save them to a file.+
−
.SH OPTIONS FOR JSHELL+
−
.TP+
−
.B \f[CB]\-\-add\-modules\f[R] \f[I]module\f[R][\f[CB],\f[R]\f[I]module\f[R]...]+
−
Specifies the root modules to resolve in addition to the initial module.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-C\f[R]\f[I]flag\f[R]+
−
Provides a flag to pass to the compiler.+
−
To pass more than one flag, provide an instance of this option for each+
−
flag or flag argument needed.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-class\-path\f[R] \f[I]path\f[R]+
−
Specifies the directories and archives that are searched to locate class+
−
files.+
−
This option overrides the path in the \f[CB]CLASSPATH\f[R] environment+
−
variable.+
−
If the environment variable isn\[aq]t set and this option isn\[aq]t+
−
used, then the current directory is searched.+
−
For Oracle Solaris, Linux, and macOS, use a colon (:) to separate items+
−
in the path.+
−
For Windows, use a semicolon (;) to separate items.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-feedback\f[R] \f[I]mode\f[R]+
−
Sets the initial level of feedback provided in response to what\[aq]s+
−
entered.+
−
The initial level can be overridden within a session by using the+
−
\f[CB]/set\ feedback\f[R] \f[I]mode\f[R] command.+
−
The default is \f[CB]normal\f[R].+
−
.RS+
−
.PP+
−
The following values are valid for \f[I]mode\f[R]:+
−
.TP+
−
.B \f[CB]verbose\f[R]+
−
Provides detailed feedback for entries.+
−
Additional information about the action performed is displayed after the+
−
result of the action.+
−
The next prompt is separated from the feedback by a blank line.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]normal\f[R]+
−
Provides an average amount of feedback.+
−
The next prompt is separated from the feedback by a blank line.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]concise\f[R]+
−
Provides minimal feedback.+
−
The next prompt immediately follows the code snippet or feedback.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]silent\f[R]+
−
Provides no feedback.+
−
The next prompt immediately follows the code snippet.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[I]custom\f[R]+
−
Provides custom feedback based on how the mode is defined.+
−
Custom feedback modes are created within JShell by using the+
−
\f[CB]/set\ mode\f[R] command.+
−
.RS+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-help\f[R] or \f[CB]\-h\f[R] or \f[CB]\-?\f[R]+
−
Prints a summary of standard options and exits the tool.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-help\-extra\f[R] or \f[CB]\-X\f[R]+
−
Prints a summary of nonstandard options and exits the tool.+
−
Nonstandard options are subject to change without notice.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-J\f[R]\f[I]flag\f[R]+
−
Provides a flag to pass to the runtime system.+
−
To pass more than one flag, provide an instance of this option for each+
−
flag or flag argument needed.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-module\-path\f[R] \f[I]modulepath\f[R]+
−
Specifies where to find application modules.+
−
For Oracle Solaris, Linux, and macOS, use a colon (:) to separate items+
−
in the path.+
−
For Windows, use a semicolon (;) to separate items.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-no\-startup\f[R]+
−
Prevents startup scripts from running when JShell starts.+
−
Use this option to run only the scripts entered on the command line when+
−
JShell is started, or to start JShell without any preloaded information+
−
if no scripts are entered.+
−
This option can\[aq]t be used if the \f[CB]\-\-startup\f[R] option is+
−
used.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-q\f[R]+
−
Sets the feedback mode to \f[CB]concise\f[R], which is the same as+
−
entering \f[CB]\-\-feedback\ concise\f[R].+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-R\f[R]\f[I]flag\f[R]+
−
Provides a flag to pass to the remote runtime system.+
−
To pass more than one flag, provide an instance of this option for each+
−
flag or flag argument to pass.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-s\f[R]+
−
Sets the feedback mode to \f[CB]silent\f[R], which is the same as entering+
−
\f[CB]\-\-feedback\ silent\f[R].+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-show\-version\f[R]+
−
Prints version information and enters the tool.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-startup\f[R] \f[I]file\f[R]+
−
Overrides the default startup script for this session.+
−
The script can contain any valid code snippets or commands.+
−
.RS+
−
.PP+
−
The script can be a local file or one of the following predefined+
−
scripts:+
−
.TP+
−
.B \f[CB]DEFAULT\f[R]+
−
Loads the default entries, which are commonly used as imports.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]JAVASE\f[R]+
−
Imports all Java SE packages.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]PRINTING\f[R]+
−
Defines \f[CB]print\f[R], \f[CB]println\f[R], and \f[CB]printf\f[R] as+
−
\f[CB]jshell\f[R] methods for use within the tool.+
−
.RS+
−
.RE+
−
.PP+
−
For more than one script, provide a separate instance of this option for+
−
each script.+
−
Startup scripts are run when JShell is first started and when the+
−
session is restarted with the \f[CB]/reset\f[R], \f[CB]/reload\f[R], or+
−
\f[CB]/env\f[R] command.+
−
Startup scripts are run in the order in which they\[aq]re entered on the+
−
command line.+
−
.PP+
−
This option can\[aq]t be used if the \f[CB]\-\-no\-startup\f[R] option is+
−
used.+
−
.RE+
−
.TP+
−
.B \f[CB]\-v\f[R]+
−
Sets the feedback mode to \f[CB]verbose\f[R], which is the same as+
−
entering \f[CB]\-\-feedback\ verbose\f[R].+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-version\f[R]+
−
Prints version information and exits the tool.+
−
.RS+
−
.RE+
−
.SH JSHELL COMMANDS+
−
.PP+
−
Within the \f[CB]jshell\f[R] tool, commands are used to modify the+
−
environment and manage code snippets.+
−
.TP+
−
.B \f[CB]/drop\f[R] {\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]} [{\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]}...]+
−
Drops snippets identified by name, ID, or ID range, making them+
−
inactive.+
−
For a range of IDs, provide the starting ID and ending ID separated with+
−
a hyphen.+
−
To provide a list, separate the items in the list with a space.+
−
Use the \f[CB]/list\f[R] command to see the IDs of code snippets.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]/edit\f[R] [\f[I]option\f[R]]+
−
Opens an editor.+
−
If no option is entered, then the editor opens with the active snippets.+
−
.RS+
−
.PP+
−
The following options are valid:+
−
.TP+
−
.B {\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]} [{\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]}...]+
−
Opens the editor with the snippets identified by name, ID, or ID range.+
−
For a range of IDs, provide the starting ID and ending ID separated with+
−
a hyphen.+
−
To provide a list, separate the items in the list with a space.+
−
Use the \f[CB]/list\f[R] command to see the IDs of code snippets.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-all\f[R]+
−
Opens the editor with all snippets, including startup snippets and+
−
snippets that failed, were overwritten, or were dropped.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-start\f[R]+
−
Opens the editor with startup snippets that were evaluated when JShell+
−
was started.+
−
.RS+
−
.RE+
−
.PP+
−
To exit edit mode, close the editor window, or respond to the prompt+
−
provided if the \f[CB]\-wait\f[R] option was used when the editor was set.+
−
.PP+
−
Use the \f[CB]/set\ editor\f[R] command to specify the editor to use.+
−
If no editor is set, then the following environment variables are+
−
checked in order: \f[CB]JSHELLEDITOR\f[R], \f[CB]VISUAL\f[R], and+
−
\f[CB]EDITOR\f[R].+
−
If no editor is set in JShell and none of the editor environment+
−
variables is set, then a simple default editor is used.+
−
.RE+
−
.TP+
−
.B \f[CB]/env\f[R] [\f[I]options\f[R]]+
−
Displays the environment settings, or updates the environment settings+
−
and restarts the session.+
−
If no option is entered, then the current environment settings are+
−
displayed.+
−
If one or more options are entered, then the session is restarted as+
−
follows:+
−
.RS+
−
.IP \[bu] 2+
−
Updates the environment settings with the provided options.+
−
.IP \[bu] 2+
−
Resets the execution state.+
−
.IP \[bu] 2+
−
Runs the startup scripts.+
−
.IP \[bu] 2+
−
Silently replays the history in the order entered.+
−
The history includes all valid snippets or \f[CB]/drop\f[R] commands+
−
entered at the \f[CB]jshell\f[R] prompt, in scripts entered on the command+
−
line, or scripts entered with the \f[CB]/open\f[R] command.+
−
.PP+
−
Environment settings entered on the command line or provided with a+
−
previous \f[CB]/reset\f[R], \f[CB]/env\f[R], or \f[CB]/reload\f[R] command are+
−
maintained unless an \f[I]option\f[R] is entered that overwrites the+
−
setting.+
−
.PP+
−
The following options are valid:+
−
.TP+
−
.B \f[CB]\-\-add\-modules\f[R] \f[I]module\f[R][\f[CB],\f[R]\f[I]module\f[R]...]+
−
Specifies the root modules to resolve in addition to the initial module.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-add\-exports\f[R] \f[I]source\-module\f[R]\f[CB]/\f[R]\f[I]package\f[R]\f[CB]=\f[R]\f[I]target\-module\f[R][\f[CB],\f[R]\f[I]target\-module\f[R]]*+
−
Adds an export of \f[I]package\f[R] from \f[I]source\-module\f[R] to+
−
\f[I]target\-module\f[R].+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-class\-path\f[R] \f[I]path\f[R]+
−
Specifies the directories and archives that are searched to locate class+
−
files.+
−
This option overrides the path in the \f[CB]CLASSPATH\f[R] environment+
−
variable.+
−
If the environment variable isn\[aq]t set and this option isn\[aq]t+
−
used, then the current directory is searched.+
−
For Oracle Solaris, Linux, and macOS, use a colon (\f[CB]:\f[R]) to+
−
separate items in the path.+
−
For Windows, use a semicolon (\f[CB];\f[R]) to separate items.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-module\-path\f[R] \f[I]modulepath\f[R]+
−
Specifies where to find application modules.+
−
For Oracle Solaris, Linux, and macOS, use a colon (\f[CB]:\f[R]) to+
−
separate items in the path.+
−
For Windows, use a semicolon (\f[CB];\f[R]) to separate items.+
−
.RS+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]/exit\f[R] [\f[I]integer\-expression\-snippet\f[R]]+
−
Exits the tool.+
−
If no snippet is entered, the exit status is zero.+
−
If a snippet is entered and the result of the snippet is an integer, the+
−
result is used as the exit status.+
−
If an error occurs, or the result of the snippet is not an integer, an+
−
error is displayed and the tool remains active.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]/history\f[R]+
−
Displays what was entered in this session.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]/help\f[R] [\f[I]command\f[R]|\f[I]subject\f[R]]+
−
Displays information about commands and subjects.+
−
If no options are entered, then a summary of information for all+
−
commands and a list of available subjects are displayed.+
−
If a valid command is provided, then expanded information for that+
−
command is displayed.+
−
If a valid subject is entered, then information about that subject is+
−
displayed.+
−
.RS+
−
.PP+
−
The following values for \f[I]subject\f[R] are valid:+
−
.TP+
−
.B \f[CB]context\f[R]+
−
Describes the options that are available for configuring the+
−
environment.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]intro\f[R]+
−
Provides an introduction to the tool.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]shortcuts\f[R]+
−
Describes keystrokes for completing commands and snippets.+
−
See \f[B]Input Shortcuts\f[R].+
−
.RS+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]/imports\f[R]+
−
Displays the current active imports, including those from the startup+
−
scripts and scripts that were entered on the command line when JShell+
−
was started.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]/list\f[R] [\f[I]option\f[R]]+
−
Displays a list of snippets and their IDs.+
−
If no option is entered, then all active snippets are displayed, but+
−
startup snippets aren\[aq]t.+
−
.RS+
−
.PP+
−
The following options are valid:+
−
.TP+
−
.B {\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]} [{\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]}...]+
−
Displays the snippets identified by name, ID, or ID range.+
−
For a range of IDs, provide the starting ID and ending ID separated with+
−
a hyphen.+
−
To provide a list, separate the items in the list with a space.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-all\f[R]+
−
Displays all snippets, including startup snippets and snippets that+
−
failed, were overwritten, or were dropped.+
−
IDs that begin with \f[CB]s\f[R] are startup snippets.+
−
IDs that begin with \f[CB]e\f[R] are snippets that failed.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-start\f[R]+
−
Displays startup snippets that were evaluated when JShell was started.+
−
.RS+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]/methods\f[R] [\f[I]option\f[R]]+
−
Displays information about the methods that were entered.+
−
If no option is entered, then the name, parameter types, and return type+
−
of all active methods are displayed.+
−
.RS+
−
.PP+
−
The following options are valid:+
−
.TP+
−
.B {\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]} [{\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]}...]+
−
Displays information for methods identified by name, ID, or ID range.+
−
For a range of IDs, provide the starting ID and ending ID separated with+
−
a hyphen.+
−
To provide a list, separate the items in the list with a space.+
−
Use the \f[CB]/list\f[R] command to see the IDs of code snippets.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-all\f[R]+
−
Displays information for all methods, including those added when JShell+
−
was started, and methods that failed, were overwritten, or were dropped.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-start\f[R]+
−
Displays information for startup methods that were added when JShell was+
−
started.+
−
.RS+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]/open\f[R] \f[I]file\f[R]+
−
Opens the script specified and reads the snippets into the tool.+
−
The script can be a local file or one of the following predefined+
−
scripts:+
−
.RS+
−
.TP+
−
.B \f[CB]DEFAULT\f[R]+
−
Loads the default entries, which are commonly used as imports.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]JAVASE\f[R]+
−
Imports all Java SE packages.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]PRINTING\f[R]+
−
Defines \f[CB]print\f[R], \f[CB]println\f[R], and \f[CB]printf\f[R] as+
−
\f[CB]jshell\f[R] methods for use within the tool.+
−
.RS+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]/reload\f[R] [\f[I]options\f[R]]+
−
Restarts the session as follows:+
−
.RS+
−
.IP \[bu] 2+
−
Updates the environment settings with the provided options, if any.+
−
.IP \[bu] 2+
−
Resets the execution state.+
−
.IP \[bu] 2+
−
Runs the startup scripts.+
−
.IP \[bu] 2+
−
Replays the history in the order entered.+
−
The history includes all valid snippets or \f[CB]/drop\f[R] commands+
−
entered at the \f[CB]jshell\f[R] prompt, in scripts entered on the command+
−
line, or scripts entered with the \f[CB]/open\f[R] command.+
−
.PP+
−
Environment settings entered on the command line or provided with a+
−
previous \f[CB]/reset\f[R], \f[CB]/env\f[R], or \f[CB]/reload\f[R] command are+
−
maintained unless an \f[I]option\f[R] is entered that overwrites the+
−
setting.+
−
.PP+
−
The following options are valid:+
−
.TP+
−
.B \f[CB]\-\-add\-modules\f[R] \f[I]module\f[R][\f[CB],\f[R]\f[I]module\f[R]...]+
−
Specifies the root modules to resolve in addition to the initial module.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-add\-exports\f[R] \f[I]source\-module\f[R]\f[CB]/\f[R]\f[I]package\f[R]\f[CB]=\f[R]\f[I]target\-module\f[R][\f[CB],\f[R]\f[I]target\-module\f[R]]*+
−
Adds an export of \f[I]package\f[R] from \f[I]source\-module\f[R] to+
−
\f[I]target\-module\f[R].+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-class\-path\f[R] \f[I]path\f[R]+
−
Specifies the directories and archives that are searched to locate class+
−
files.+
−
This option overrides the path in the \f[CB]CLASSPATH\f[R] environment+
−
variable.+
−
If the environment variable isn\[aq]t set and this option isn\[aq]t+
−
used, then the current directory is searched.+
−
For Oracle Solaris, Linux, and macOS, use a colon (\f[CB]:\f[R]) to+
−
separate items in the path.+
−
For Windows, use a semicolon (\f[CB];\f[R]) to separate items.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-module\-path\f[R] \f[I]modulepath\f[R]+
−
Specifies where to find application modules.+
−
For Oracle Solaris, Linux, and macOS, use a colon (\f[CB]:\f[R]) to+
−
separate items in the path.+
−
For Windows, use a semicolon (\f[CB];\f[R]) to separate items.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-quiet\f[R]+
−
Replays the valid history without displaying it.+
−
Errors are displayed.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-restore\f[R]+
−
Resets the environment to the state at the start of the previous run of+
−
the tool or to the last time a \f[CB]/reset\f[R], \f[CB]/reload\f[R], or+
−
\f[CB]/env\f[R] command was executed in the previous run.+
−
The valid history since that point is replayed.+
−
Use this option to restore a previous JShell session.+
−
.RS+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]/reset\f[R] [\f[I]options\f[R]]+
−
Discards all entered snippets and restarts the session as follows:+
−
.RS+
−
.IP \[bu] 2+
−
Updates the environment settings with the provided options, if any.+
−
.IP \[bu] 2+
−
Resets the execution state.+
−
.IP \[bu] 2+
−
Runs the startup scripts.+
−
.PP+
−
History is not replayed.+
−
All code that was entered is lost.+
−
.PP+
−
Environment settings entered on the command line or provided with a+
−
previous \f[CB]/reset\f[R], \f[CB]/env\f[R], or \f[CB]/reload\f[R] command are+
−
maintained unless an \f[I]option\f[R] is entered that overwrites the+
−
setting.+
−
.PP+
−
The following options are valid:+
−
.TP+
−
.B \f[CB]\-\-add\-modules\f[R] \f[I]module\f[R][\f[CB],\f[R]\f[I]module\f[R]...]+
−
Specifies the root modules to resolve in addition to the initial module.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-add\-exports\f[R] \f[I]source\-module\f[R]\f[CB]/\f[R]\f[I]package\f[R]\f[CB]=\f[R]\f[I]target\-module\f[R][\f[CB],\f[R]\f[I]target\-module\f[R]]*+
−
Adds an export of \f[I]package\f[R] from \f[I]source\-module\f[R] to+
−
\f[I]target\-module\f[R].+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-class\-path\f[R] \f[I]path\f[R]+
−
Specifies the directories and archives that are searched to locate class+
−
files.+
−
This option overrides the path in the \f[CB]CLASSPATH\f[R] environment+
−
variable.+
−
If the environment variable isn\[aq]t set and this option isn\[aq]t+
−
used, then the current directory is searched.+
−
For Oracle Solaris, Linux, and macOS, use a colon (\f[CB]:\f[R]) to+
−
separate items in the path.+
−
For Windows, use a semicolon (\f[CB];\f[R]) to separate items.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-\-module\-path\f[R] \f[I]modulepath\f[R]+
−
Specifies where to find application modules.+
−
For Oracle Solaris, Linux, and macOS, use a colon (\f[CB]:\f[R]) to+
−
separate items in the path.+
−
For Windows, use a semicolon (\f[CB];\f[R]) to separate items.+
−
.RS+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]/save\f[R] [\f[I]options\f[R]] \f[I]file\f[R]+
−
Saves snippets and commands to the file specified.+
−
If no options are entered, then active snippets are saved.+
−
.RS+
−
.PP+
−
The following options are valid:+
−
.TP+
−
.B {\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]} [{\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]}...]+
−
Saves the snippets and commands identified by name, ID, or ID range.+
−
For a range of IDs, provide the starting ID and ending ID separated with+
−
a hyphen.+
−
To provide a list, separate the items in the list with a space.+
−
Use the \f[CB]/list\f[R] command to see the IDs of the code snippets.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-all\f[R]+
−
Saves all snippets, including startup snippets and snippets that were+
−
overwritten or failed.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-history\f[R]+
−
Saves the sequential history of all commands and snippets entered in the+
−
current session.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-start\f[R]+
−
Saves the current startup settings.+
−
If no startup scripts were provided, then an empty file is saved.+
−
.RS+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]/set\f[R] [\f[I]setting\f[R]]+
−
Sets configuration information, including the external editor, startup+
−
settings, and feedback mode.+
−
This command is also used to create a custom feedback mode with+
−
customized prompt, format, and truncation values.+
−
If no setting is entered, then the current setting for the editor,+
−
startup settings, and feedback mode are displayed.+
−
.RS+
−
.PP+
−
The following values are valid for \f[CB]setting\f[R]:+
−
.TP+
−
.B \f[CB]editor\f[R] [\f[I]options\f[R]] [\f[I]command\f[R]]+
−
Sets the command used to start an external editor when the+
−
\f[CB]/edit\f[R] command is entered.+
−
The command can include command arguments separated by spaces.+
−
If no command or options are entered, then the current setting is+
−
displayed.+
−
.RS+
−
.PP+
−
The following options are valid:+
−
.TP+
−
.B \f[CB]\-default\f[R]+
−
Sets the editor to the default editor provided with JShell.+
−
This option can\[aq]t be used if a command for starting an editor is+
−
entered.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-delete\f[R]+
−
Sets the editor to the one in effect when the session started.+
−
If used with the \f[CB]\-retain\f[R] option, then the retained editor+
−
setting is deleted and the editor is set to the first of the following+
−
environment variables found: \f[CB]JSHELLEDITOR\f[R], \f[CB]VISUAL\f[R], or+
−
\f[CB]EDITOR\f[R].+
−
If none of the editor environment variables are set, then this option+
−
sets the editor to the default editor.+
−
.RS+
−
.PP+
−
This option can\[aq]t be used if a command for starting an editor is+
−
entered.+
−
.RE+
−
.TP+
−
.B \f[CB]\-retain\f[R]+
−
Saves the editor setting across sessions.+
−
If no other option or a command is entered, then the current setting is+
−
saved.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-wait\f[R]+
−
Prompts the user to indicate when editing is complete.+
−
Otherwise control returns to JShell when the editor exits.+
−
Use this option if the editor being used exits immediately, for example,+
−
when an edit window already exists.+
−
This option is valid only when a command for starting an editor is+
−
entered.+
−
.RS+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]feedback\f[R] [\f[I]mode\f[R]]+
−
Sets the feedback mode used to respond to input.+
−
If no mode is entered, then the current mode is displayed.+
−
.RS+
−
.PP+
−
The following modes are valid: \f[CB]concise\f[R], \f[CB]normal\f[R],+
−
\f[CB]silent\f[R], \f[CB]verbose\f[R], and any custom mode created with the+
−
\f[CB]/set\ mode\f[R] command.+
−
.RE+
−
.TP+
−
.B \f[CB]format\f[R] \f[I]mode\f[R] \f[I]field\f[R] \f[CB]"\f[R]\f[I]format\-string\f[R]\f[CB]"\f[R] \f[I]selector\f[R]+
−
Sets the format of the feedback provided in response to input.+
−
If no mode is entered, then the current formats for all fields for all+
−
feedback modes are displayed.+
−
If only a mode is entered, then the current formats for that mode are+
−
displayed.+
−
If only a mode and field are entered, then the current formats for that+
−
field are displayed.+
−
.RS+
−
.PP+
−
To define a format, the following arguments are required:+
−
.TP+
−
.B \f[I]mode\f[R]+
−
Specifies a feedback mode to which the response format is applied.+
−
Only custom modes created with the \f[CB]/set\ mode\f[R] command can be+
−
modified.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[I]field\f[R]+
−
Specifies a context\-specific field to which the response format is+
−
applied.+
−
The fields are described in the online help, which is accessed from+
−
JShell using the \f[CB]/help\ /set\ format\f[R] command.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]"\f[R]\f[I]format\-string\f[R]\f[CB]"\f[R]+
−
Specifies the string to use as the response format for the specified+
−
field and selector.+
−
The structure of the format string is described in the online help,+
−
which is accessed from JShell using the \f[CB]/help\ /set\ format\f[R]+
−
command.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[I]selector\f[R]+
−
Specifies the context in which the response format is applied.+
−
The selectors are described in the online help, which is accessed from+
−
JShell using the \f[CB]/help\ /set\ format\f[R] command.+
−
.RS+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]mode\f[R] [\f[I]mode\-name\f[R]] [\f[I]existing\-mode\f[R]] [\f[I]options\f[R]]+
−
Creates a custom feedback mode with the mode name provided.+
−
If no mode name is entered, then the settings for all modes are+
−
displayed, which includes the mode, prompt, format, and truncation+
−
settings.+
−
If the name of an existing mode is provided, then the settings from the+
−
existing mode are copied to the mode being created.+
−
.RS+
−
.PP+
−
The following options are valid:+
−
.TP+
−
.B \f[CB]\-command\f[R]|\f[CB]\-quiet\f[R]+
−
Specifies the level of feedback displayed for commands when using the+
−
mode.+
−
This option is required when creating a feedback mode.+
−
Use \f[CB]\-command\f[R] to show information and verification feedback for+
−
commands.+
−
Use \f[CB]\-quiet\f[R] to show only essential feedback for commands, such+
−
as error messages.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-delete\f[R]+
−
Deletes the named feedback mode for this session.+
−
The name of the mode to delete is required.+
−
To permanently delete a retained mode, use the \f[CB]\-retain\f[R] option+
−
with this option.+
−
Predefined modes can\[aq]t be deleted.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-retain\f[R]+
−
Saves the named feedback mode across sessions.+
−
The name of the mode to retain is required.+
−
.RS+
−
.RE+
−
.PP+
−
Configure the new feedback mode using the \f[CB]/set\ prompt\f[R],+
−
\f[CB]/set\ format\f[R], and \f[CB]/set\ truncation\f[R] commands.+
−
.PP+
−
To start using the new mode, use the \f[CB]/set\ feedback\f[R] command.+
−
.RE+
−
.TP+
−
.B \f[CB]prompt\f[R] \f[I]mode\f[R] \f[CB]"\f[R]\f[I]prompt\-string\f[R]\f[CB]"\f[R] \f[CB]"\f[R]\f[I]continuation\-prompt\-string\f[R]\f[CB]"\f[R]+
−
Sets the prompts for input within JShell.+
−
If no mode is entered, then the current prompts for all feedback modes+
−
are displayed.+
−
If only a mode is entered, then the current prompts for that mode are+
−
displayed.+
−
.RS+
−
.PP+
−
To define a prompt, the following arguments are required:+
−
.TP+
−
.B \f[I]mode\f[R]+
−
Specifies the feedback mode to which the prompts are applied.+
−
Only custom modes created with the \f[CB]/set\ mode\f[R] command can be+
−
modified.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]"\f[R]\f[I]prompt\-string\f[R]\f[CB]"\f[R]+
−
Specifies the string to use as the prompt for the first line of input.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]"\f[R]\f[I]continuation\-prompt\-string\f[R]\f[CB]"\f[R]+
−
Specifies the string to use as the prompt for the additional input lines+
−
needed to complete a snippet.+
−
.RS+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]start\f[R] [\f[CB]\-retain\f[R]] [\f[I]file\f[R] [\f[I]file\f[R]...]|\f[I]option\f[R]]+
−
Sets the names of the startup scripts used when the next+
−
\f[CB]/reset\f[R], \f[CB]/reload\f[R], or \f[CB]/env\f[R] command is entered.+
−
If more than one script is entered, then the scripts are run in the+
−
order entered.+
−
If no scripts or options are entered, then the current startup settings+
−
are displayed.+
−
.RS+
−
.PP+
−
The scripts can be local files or one of the following predefined+
−
scripts:+
−
.TP+
−
.B \f[CB]DEFAULT\f[R]+
−
Loads the default entries, which are commonly used as imports.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]JAVASE\f[R]+
−
Imports all Java SE packages.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]PRINTING\f[R]+
−
Defines \f[CB]print\f[R], \f[CB]println\f[R], and \f[CB]printf\f[R] as+
−
\f[CB]jshell\f[R] methods for use within the tool.+
−
.RS+
−
.RE+
−
.PP+
−
The following options are valid:+
−
.TP+
−
.B \f[CB]\-default\f[R]+
−
Sets the startup settings to the default settings.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-none\f[R]+
−
Specifies that no startup settings are used.+
−
.RS+
−
.RE+
−
.PP+
−
Use the \f[CB]\-retain\f[R] option to save the start setting across+
−
sessions.+
−
.RE+
−
.TP+
−
.B \f[CB]truncation\f[R] \f[I]mode\f[R] \f[I]length\f[R] \f[I]selector\f[R]+
−
Sets the maximum length of a displayed value.+
−
If no mode is entered, then the current truncation values for all+
−
feedback modes are displayed.+
−
If only a mode is entered, then the current truncation values for that+
−
mode are displayed.+
−
.RS+
−
.PP+
−
To define truncation values, the following arguments are required:+
−
.TP+
−
.B \f[I]mode\f[R]+
−
Specifies the feedback mode to which the truncation value is applied.+
−
Only custom modes created with the \f[CB]/set\ mode\f[R] command can be+
−
modified.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[I]length\f[R]+
−
Specifies the unsigned integer to use as the maximum length for the+
−
specified selector.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[I]selector\f[R]+
−
Specifies the context in which the truncation value is applied.+
−
The selectors are described in the online help, which is accessed from+
−
JShell using the \f[CB]/help\ /set\ truncation\f[R] command.+
−
.RS+
−
.RE+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]/types\f[R] [\f[I]option\f[R]]+
−
Displays classes, interfaces, and enums that were entered.+
−
If no option is entered, then all current active classes, interfaces,+
−
and enums are displayed.+
−
.RS+
−
.PP+
−
The following options are valid:+
−
.TP+
−
.B {\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]} [{\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]}...]+
−
Displays information for classes, interfaces, and enums identified by+
−
name, ID, or ID range.+
−
For a range of IDs, provide the starting ID and ending ID separated with+
−
a hyphen.+
−
To provide a list, separate the items in the list with a space.+
−
Use the \f[CB]/list\f[R] command to see the IDs of the code snippets.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-all\f[R]+
−
Displays information for all classes, interfaces, and enums, including+
−
those added when JShell was started, and classes, interfaces, and enums+
−
that failed, were overwritten, or were dropped.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-start\f[R]+
−
Displays information for startup classes, interfaces, and enums that+
−
were added when JShell was started.+
−
.RS+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]/vars\f[R] [\f[I]option\f[R]]+
−
Displays the name, type, and value of variables that were entered.+
−
If no option is entered, then all current active variables are+
−
displayed.+
−
.RS+
−
.PP+
−
The following options are valid:+
−
.TP+
−
.B {\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]} [{\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]}...]+
−
Displays information for variables identified by name, ID, or ID range.+
−
For a range of IDs, provide the starting ID and ending ID separated with+
−
a hyphen.+
−
To provide a list, separate the items in the list with a space.+
−
Use the \f[CB]/list\f[R] command to see the IDs of the code snippets.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-all\f[R]+
−
Displays information for all variables, including those added when+
−
JShell was started, and variables that failed, were overwritten, or were+
−
dropped.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]\-start\f[R]+
−
Displays information for startup variables that were added when JShell+
−
was started.+
−
.RS+
−
.RE+
−
.RE+
−
.TP+
−
.B \f[CB]/?\f[R]+
−
Same as the \f[CB]/help\f[R] command.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]/!\f[R]+
−
Reruns the last snippet.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]/\f[R]{\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]} [{\f[I]name\f[R]|\f[I]id\f[R]|\f[I]startID\f[R]\f[CB]\-\f[R]\f[I]endID\f[R]}...]+
−
Reruns the snippets identified by ID, range of IDs, or name.+
−
For a range of IDs, provide the starting ID and ending ID separated with+
−
a hyphen.+
−
To provide a list, separate the items in the list with a space.+
−
The first item in the list must be an ID or ID range.+
−
Use the \f[CB]/list\f[R] command to see the IDs of the code snippets.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[CB]/\-\f[R]\f[I]n\f[R]+
−
Reruns the \-\f[I]n\f[R]th previous snippet.+
−
For example, if 15 code snippets were entered, then \f[CB]/\-4\f[R] runs+
−
the 11th snippet.+
−
Commands aren\[aq]t included in the count.+
−
.RS+
−
.RE+
−
.SH INPUT SHORTCUTS+
−
.PP+
−
The following shortcuts are available for entering commands and snippets+
−
in JShell.+
−
.SS Tab completion+
−
.TP+
−
.B \f[B]<tab>\f[R]+
−
When entering snippets, commands, subcommands, command arguments, or+
−
command options, use the Tab key to automatically complete the item.+
−
If the item can\[aq]t be determined from what was entered, then possible+
−
options are provided.+
−
.RS+
−
.PP+
−
When entering a method call, use the Tab key after the method call\[aq]s+
−
opening parenthesis to see the parameters for the method.+
−
If the method has more than one signature, then all signatures are+
−
displayed.+
−
Pressing the Tab key a second time displays the description of the+
−
method and the parameters for the first signature.+
−
Continue pressing the Tab key for a description of any additional+
−
signatures.+
−
.RE+
−
.TP+
−
.B \f[B]Shift+<Tab> V\f[R]+
−
After entering a complete expression, use this key sequence to convert+
−
the expression to a variable declaration of a type determined by the+
−
type of the expression.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[B]Shift+<Tab> M\f[R]+
−
After entering a complete expression or statement, use this key sequence+
−
to convert the expression or statement to a method declaration.+
−
If an expression is entered, the return type is based on the type of the+
−
expression.+
−
.RS+
−
.RE+
−
.TP+
−
.B \f[B]Shift+<Tab> I\f[R]+
−
When an identifier is entered that can\[aq]t be resolved, use this key+
−
sequence to show possible imports that resolve the identifier based on+
−
the content of the specified class path.+
−
.RS+
−
.RE+
−
.SS Command abbreviations+
−
.PP+
−
An abbreviation of a command is accepted if the abbreviation uniquely+
−
identifies a command.+
−
For example, \f[CB]/l\f[R] is recognized as the \f[CB]/list\f[R] command.+
−
However, \f[CB]/s\f[R] isn\[aq]t a valid abbreviation because it can\[aq]t+
−
be determined if the \f[CB]/set\f[R] or \f[CB]/save\f[R] command is meant.+
−
Use \f[CB]/se\f[R] for the \f[CB]/set\f[R] command or \f[CB]/sa\f[R] for the+
−
\f[CB]/save\f[R] command.+
−
.PP+
−
Abbreviations are also accepted for subcommands, command arguments, and+
−
command options.+
−
For example, use \f[CB]/m\ \-a\f[R] to display all methods.+
−
.SS History navigation+
−
.PP+
−
A history of what was entered is maintained across sessions.+
−
Use the up and down arrows to scroll through commands and snippets from+
−
the current and past sessions.+
−
Use the Ctrl key with the up and down arrows to skip all but the first+
−
line of multiline snippets.+
−
.SS History search+
−
.PP+
−
Use the Ctrl+R key combination to search the history for the string+
−
entered.+
−
The prompt changes to show the string and the match.+
−
Ctrl+R searches backwards from the current location in the history+
−
through earlier entries.+
−
Ctrl+S searches forward from the current location in the history though+
−
later entries.+
−
.SH INPUT EDITING+
−
.PP+
−
The editing capabilities of JShell are similar to that of other common+
−
shells.+
−
Keyboard keys and key combinations provide line editing shortcuts.+
−
The Ctrl key and Meta key are used in key combinations.+
−
If your keyboard doesn\[aq]t have a Meta key, then the Alt key is often+
−
mapped to provide Meta key functionality.+
−
.PP+
−
.TS+
−
tab(@);+
−
l l.+
−
T{+
−
Key or Key Combination+
−
T}@T{+
−
Action+
−
T}+
−
_+
−
T{+
−
Return+
−
T}@T{+
−
Enter the current line.+
−
T}+
−
T{+
−
Left arrow+
−
T}@T{+
−
Move the cursor to the left one character.+
−
T}+
−
T{+
−
Right arrow+
−
T}@T{+
−
Move the cursor to the right one character.+
−
T}+
−
T{+
−
Ctrl+A+
−
T}@T{+
−
Move the cursor to the beginning of the line.+
−
T}+
−
T{+
−
Ctrl+E+
−
T}@T{+
−
Move the cursor to the end of the line.+
−
T}+
−
T{+
−
Meta+B+
−
T}@T{+
−
Move the cursor to the left one word.+
−
T}+
−
T{+
−
Meta+F+
−
T}@T{+
−
Move the cursor to the right one word.+
−
T}+
−
T{+
−
Delete+
−
T}@T{+
−
Delete the character under the cursor.+
−
T}+
−
T{+
−
Backspace+
−
T}@T{+
−
Delete the character before the cursor.+
−
T}+
−
T{+
−
Ctrl+K+
−
T}@T{+
−
Delete the text from the cursor to the end of the line.+
−
T}+
−
T{+
−
Meta+D+
−
T}@T{+
−
Delete the text from the cursor to the end of the word.+
−
T}+
−
T{+
−
Ctrl+W+
−
T}@T{+
−
Delete the text from the cursor to the previous white space.+
−
T}+
−
T{+
−
Ctrl+Y+
−
T}@T{+
−
Paste the most recently deleted text into the line.+
−
T}+
−
T{+
−
Meta+Y+
−
T}@T{+
−
After Ctrl+Y, press to cycle through the previously deleted text.+
−
T}+
−
.TE+
−
.SH EXAMPLE OF STARTING AND STOPPING A JSHELL SESSION+
−
.PP+
−
JShell is provided with the JDK.+
−
To start a session, enter \f[CB]jshell\f[R] on the command line.+
−
A welcome message is printed, and a prompt for entering commands and+
−
snippets is provided.+
−
.IP+
−
.nf+
−
\f[CB]+
−
%\ jshell+
−
|\ \ Welcome\ to\ JShell\ \-\-\ Version\ 9+
−
|\ \ For\ an\ introduction\ type:\ /help\ intro+
−
+
−
jshell>+
−
\f[R]+
−
.fi+
−
.PP+
−
To see which snippets were automatically loaded when JShell started, use+
−
the \f[CB]/list\ \-start\f[R] command.+
−
The default startup snippets are import statements for common packages.+
−
The ID for each snippet begins with the letter \f[I]s\f[R], which+
−
indicates it\[aq]s a startup snippet.+
−
.IP+
−
.nf+
−
\f[CB]+
−
jshell>\ /list\ \-start+
−
+
−
\ \ s1\ :\ import\ java.io.*;+
−
\ \ s2\ :\ import\ java.math.*;+
−
\ \ s3\ :\ import\ java.net.*;+
−
\ \ s4\ :\ import\ java.nio.file.*;+
−
\ \ s5\ :\ import\ java.util.*;+
−
\ \ s6\ :\ import\ java.util.concurrent.*;+
−
\ \ s7\ :\ import\ java.util.function.*;+
−
\ \ s8\ :\ import\ java.util.prefs.*;+
−
\ \ s9\ :\ import\ java.util.regex.*;+
−
\ s10\ :\ import\ java.util.stream.*;+
−
+
−
jshell>+
−
\f[R]+
−
.fi+
−
.PP+
−
To end the session, use the \f[CB]/exit\f[R] command.+
−
.IP+
−
.nf+
−
\f[CB]+
−
jshell>\ /exit+
−
|\ \ Goodbye+
−
+
−
%+
−
\f[R]+
−
.fi+
−
.SH EXAMPLE OF ENTERING SNIPPETS+
−
.PP+
−
Snippets are Java statements, variable definitions, method definitions,+
−
class definitions, import statements, and expressions.+
−
Terminating semicolons are automatically added to the end of a completed+
−
snippet if they\[aq]re missing.+
−
.PP+
−
The following example shows two variables and a method being defined,+
−
and the method being run.+
−
Note that a scratch variable is automatically created to hold the result+
−
because no variable was provided.+
−
.IP+
−
.nf+
−
\f[CB]+
−
jshell>\ int\ a=4+
−
a\ ==>\ 4+
−
+
−
jshell>\ int\ b=8+
−
b\ ==>\ 8+
−
+
−
jshell>\ int\ square(int\ i1)\ {+
−
\ \ \ ...>\ return\ i1\ *\ i1;+
−
\ \ \ ...>\ }+
−
|\ \ created\ method\ square(int)+
−
+
−
jshell>\ square(b)+
−
$5\ ==>\ 64+
−
\f[R]+
−
.fi+
−
.SH EXAMPLE OF CHANGING SNIPPETS+
−
.PP+
−
Change the definition of a variable, method, or class by entering it+
−
again.+
−
.PP+
−
The following examples shows a method being defined and the method run:+
−
.IP+
−
.nf+
−
\f[CB]+
−
jshell>\ String\ grade(int\ testScore)\ {+
−
\ \ \ ...>\ \ \ \ \ if\ (testScore\ >=\ 90)\ {+
−
\ \ \ ...>\ \ \ \ \ \ \ \ \ return\ "Pass";+
−
\ \ \ ...>\ \ \ \ \ }+
−
\ \ \ ...>\ \ \ \ \ return\ "Fail";+
−
\ \ \ ...>\ }+
−
|\ \ created\ method\ grade(int)+
−
+
−
jshell>\ grade(88)+
−
$3\ ==>\ "Fail"+
−
\f[R]+
−
.fi+
−
.PP+
−
To change the method \f[CB]grade\f[R] to allow more students to pass,+
−
enter the method definition again and change the pass score to+
−
\f[CB]80\f[R].+
−
Use the up arrow key to retrieve the previous entries to avoid having to+
−
reenter them and make the change in the \f[CB]if\f[R] statement.+
−
The following example shows the new definition and reruns the method to+
−
show the new result:+
−
.IP+
−
.nf+
−
\f[CB]+
−
jshell>\ String\ grade(int\ testScore)\ {+
−
\ \ \ ...>\ \ \ \ \ if\ (testScore\ >=\ 80)\ {+
−
\ \ \ ...>\ \ \ \ \ \ \ \ \ return\ "Pass";+
−
\ \ \ ...>\ \ \ \ \ }+
−
\ \ \ ...>\ \ \ \ \ return\ "Fail";+
−
\ \ \ ...>\ }+
−
|\ \ modified\ method\ grade(int)+
−
+
−
jshell>\ grade(88)+
−
$5\ ==>\ "Pass"+
−
\f[R]+
−
.fi+
−
.PP+
−
For snippets that are more than a few lines long, or to make more than a+
−
few changes, use the \f[CB]/edit\f[R] command to open the snippet in an+
−
editor.+
−
After the changes are complete, close the edit window to return control+
−
to the JShell session.+
−
The following example shows the command and the feedback provided when+
−
the edit window is closed.+
−
The \f[CB]/list\f[R] command is used to show that the pass score was+
−
changed to \f[CB]85\f[R].+
−
.IP+
−
.nf+
−
\f[CB]+
−
jshell>\ /edit\ grade+
−
|\ \ modified\ method\ grade(int)+
−
jshell>\ /list\ grade+
−
+
−
\ \ \ 6\ :\ String\ grade(int\ testScore)\ {+
−
\ \ \ \ \ \ \ \ \ \ \ if\ (testScore\ >=\ 85)\ {+
−
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ return\ "Pass";+
−
\ \ \ \ \ \ \ \ \ \ \ }+
−
\ \ \ \ \ \ \ \ \ \ \ return\ "Fail";+
−
\ \ \ \ \ \ \ }+
−
\f[R]+
−
.fi+
−
.SH EXAMPLE OF CREATING A CUSTOM FEEDBACK MODE+
−
.PP+
−
The feedback mode determines the prompt that\[aq]s displayed, the+
−
feedback messages that are provided as snippets are entered, and the+
−
maximum length of a displayed value.+
−
Predefined feedback modes are provided.+
−
Commands for creating custom feedback modes are also provided.+
−
.PP+
−
Use the \f[CB]/set\ mode\f[R] command to create a new feedback mode.+
−
In the following example, the new mode \f[CB]mymode\f[R], is based on the+
−
predefined feedback mode, \f[CB]normal\f[R], and verifying command+
−
feedback is displayed:+
−
.IP+
−
.nf+
−
\f[CB]+
−
jshell>\ /set\ mode\ mymode\ normal\ \-command+
−
|\ \ Created\ new\ feedback\ mode:\ mymode+
−
\f[R]+
−
.fi+
−
.PP+
−
Because the new mode is based on the \f[CB]normal\f[R] mode, the prompts+
−
are the same.+
−
The following example shows how to see what prompts are used and then+
−
changes the prompts to custom strings.+
−
The first string represents the standard JShell prompt.+
−
The second string represents the prompt for additional lines in+
−
multiline snippets.+
−
.IP+
−
.nf+
−
\f[CB]+
−
jshell>\ /set\ prompt\ mymode+
−
|\ \ /set\ prompt\ mymode\ "\\njshell>\ "\ "\ \ \ ...>\ "+
−
+
−
jshell>\ /set\ prompt\ mymode\ "\\nprompt$\ "\ "\ \ \ continue$\ "+
−
\f[R]+
−
.fi+
−
.PP+
−
The maximum length of a displayed value is controlled by the truncation+
−
setting.+
−
Different types of values can have different lengths.+
−
The following example sets an overall truncation value of 72, and a+
−
truncation value of 500 for variable value expressions:+
−
.IP+
−
.nf+
−
\f[CB]+
−
jshell>\ /set\ truncation\ mymode\ 72+
−
+
−
jshell>\ /set\ truncation\ mymode\ 500\ varvalue+
−
\f[R]+
−
.fi+
−
.PP+
−
The feedback displayed after snippets are entered is controlled by the+
−
format setting and is based on the type of snippet entered and the+
−
action taken for that snippet.+
−
In the predefined mode \f[CB]normal\f[R], the string \f[CB]created\f[R] is+
−
displayed when a method is created.+
−
The following example shows how to change that string to+
−
\f[CB]defined\f[R]:+
−
.IP+
−
.nf+
−
\f[CB]+
−
jshell>\ /set\ format\ mymode\ action\ "defined"\ added\-primary+
−
\f[R]+
−
.fi+
−
.PP+
−
Use the \f[CB]/set\ feedback\f[R] command to start using the feedback mode+
−
that was just created.+
−
The following example shows the custom mode in use:+
−
.IP+
−
.nf+
−
\f[CB]+
−
jshell>\ /set\ feedback\ mymode+
−
|\ \ Feedback\ mode:\ mymode+
−
+
−
prompt$\ int\ square\ (int\ num1){+
−
\ \ \ continue$\ return\ num1*num1;+
−
\ \ \ continue$\ }+
−
|\ \ defined\ method\ square(int)+
−
+
−
prompt$+
−
\f[R]+
−
.fi+
−