How can we execute snippets by ID in JShell in Java 9?

JShell is an interactive tool (REPL) introduced in Java 9. We can execute snippets like expressions, variables, methods, classes, and etc without a main () method in the JShell tool.

We can execute any prior snippet by simply typing /id, which indicates the snippet’s ID. For instance, if we type "/1", then JShell can display the first snippet that we have entered, executes it, and shows the result. We can re-execute the last snippet that we have entered (whether it is valid or invalid) by using "/!".

In the below code snippet, we have created a set of snippets, and execute those snippets by using /1, /2, /3, and /4.

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

jshell> 2+10
$1 ==> 12

jshell> String s = "Tutorialspoint"
s ==> "Tutorialspoint"

jshell> System.out.println("Tutorialspoint")
Tutorialspoint

jshell> int num1 = 25
num1 ==> 25

jshell> /1
2+10
$5 ==> 12

jshell> /2
String s = "Tutorialspoint";
s ==> "Tutorialspoint"

jshell> /3
System.out.println("Tutorialspoint")
Tutorialspoint

jshell> /4
int num1 = 25;
num1 ==> 25

In the below code snippet, we can able to re-execute the last snippet by using "/!" command.

jshell> 2+5
$1 ==> 7

jshell> 10-6
$2 ==> 4

jshell> /1
2+5
$3 ==> 7

jshell> /!
2+5
$4 ==> 7