JShell is an interactive tool for learning the Java language and prototyping Java code. It is a REPL (Read-Evaluate-Print-Loop) that evaluates declarations, statements, and expressions once entered and immediately prints the results in JShell. This tool runs from the command-line prompt.
The modifiers like public, protected, private, static, and final have not allowed on top-level declarations and can be ignored with a warning. The keywords like synchronized, native, abstract, and default top-level methods have not allowed and can be errors.
In the below code snippets, we have created both final and static variables. It prints out a warning message to the user that "Modifier 'final' or 'static' not permitted in top-level declarations, ignored".
C:\Users\User\>jshell | Welcome to JShell -- Version 9.0.4 | For an introduction type: /help intro jshell> final int x = 0 | Warning: | Modifier 'final' not permitted in top-level declarations, ignored | final int x = 0; | ^---^ x ==> 0 jshell> x = 1 x ==> 1
jshell> static String str = "Tutorix" | Warning: | Modifier 'static' not permitted in top-level declarations, ignored | static String str = "Tutorix"; | ^----^ str ==> "Tutorix"