Avoid Compilation Errors in JShell in Java 9

JShell is an interactive tool that enables us to execute java code and displays the output instantly. JShell is the REPL(Read-Evaluate-Print-Loop) tool that runs from the command-line prompt. If we need to avoid the compilation-errors in JShell, then we must declare those variables before using it. The error message in JShell can use the notation "^--^" to highlight an error.

In the below code snippet, the declaration of an int variable "div" attempts to use variables: num1, and num2 that has not been declared, so JShell reports a compilation error, indicating that the compiler was unable to find those variables.

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

jshell> int div = num1 / num2
|  Error:
|  cannot find symbol
|  symbol: variable num1
|  int div = num1 / num2;
|  ^--^
|  Error:
|  cannot find symbol
|  symbol: variable num2
|  int div = num1 / num2;
|  ^--^

In the below code snippet, JShell displays the variable’s name: num1 and num2 followed by double equal and greater-than signs (==>).

jshell> int num1 = 35
num1 ==> 35

jshell> int num2 = 7
num2 ==> 7

jshell> int div = num1 / num2
div ==> 5