Working with JShell

jshell_en.md

Working with JShell

What is JShell?

JShell is a tool that lets you execute Java code interactively. It is part of the JDK, starting with Java SE 9.

Commands

JShell commands control the environment and display information within a session.

Useful commands:

Command	Description
/exit	Exits JShell (nothing is saved).
/help	Displays help about using JShell.
/history	Lists the snippets and commands entered.
/imports	Lists the current active imports.
/list	Lists the snippets entered.
/methods	Lists the methods entered.
/reset	Resets JShell (clears snippets entered).
/save <file>	Saves the snippets entered.
/save <id> <file>	Saves the snippet specified.
/vars	Lists the variables entered.
/!	Reevaluates the last snippet.
/<id>	Reevaluates the snippet specified.

Editing

External Editor

Setting an external editor:

/set editor gedit

Editing all existing snippets:

/edit

When you save in the editor, any changed or new snippet is entered into the JShell session.

Editing a specific snippet:

/edit <id>

Feedback Modes

The feedback mode determines the prompts, feedback, and other interactions within JShell.

Showing the current feedback mode:

/set feedback

Setting the feedback mode:

/set feedback verbose
/set feedback normal
/set feedback concise
/set feedback silent

Loading Scripts

A JShell script is a sequence of snippets and JShell commands in a file, one snippet or command per line.

Starting JShell with executing a script:

$ jshell <file>

Reading and executing a script in JShell:

/open <file>

Important Notes

Code in the default package can't be accessed from JShell.

Tool Support

• Apache Maven: jshell-maven-plugin

• Gradle: jshell-plugin

• IntelliJ IDEA: JShell Console

  • Issues: https://youtrack.jetbrains.com/issues/IDEA?q=jshell

References

Java Shell User's Guide, Release 21