I am working with jshell of JDK9.
I just created a final variable and assigned a value to it.
And in the next line i just modified the value. And to my surprise, there was no error when modifying the final variables.
Here is the code snippets:
jshell> final int r = 0;
| Warning:
| Modifier 'final' not permitted in top-level declarations, ignored
| final int r = 0;
| ^---^
r ==> 0
jshell> r = 1;
r ==> 1
jshell> System.out.println("r = "+r)
r = 1
Is it what is expected from jshell? or there is some other way to work with final variables in jshell?
While creating a final variable at the top-level is not supposed to be practiced. But I guess there is no hard way of restricting such usages.
From the documentation around JShell.eval
The modifiers public
, protected
, private
, static
, and final
are not
allowed on op-level declarations and are ignored with a warning.
Synchronized, native, abstract, and default top-level methods are not
allowed and are errors.
If a previous definition of a declaration is
overwritten then there will be an event showing its status changed to
OVERWRITTEN, this will not occur for dropped, rejected, or already
overwritten declarations.
The warning stated above is quite visible when you execute jshell
in verbose mode as follows: