Why can I re-assign a new value to a final variable in Android AIDE?

Question

How this is possible? How am I able to change variables marked as final?

public class Main
{
    public static void main(String[] args)
    {
        final int NUM;

        NUM = 22;
        NUM = 33;

        System.out.println(NUM);
    }

}

I was using AIDE app in Android... it compiled successfully and printed 33.

Possible duplicate of [How does the "final" keyword in Java work? (I can still modify an object.)](https://stackoverflow.com/questions/15655012/how-does-the-final-keyword-in-java-work-i-can-still-modify-an-object) — franiis, Sep 16 '18 at 07:15
Tried your code and getting a compile error `The final local variable NUM may already have been assigned` as expected. — Yug Singh, Sep 16 '18 at 07:15
A final variable once declared can't be re assigned a new value — Umer Farooq, Sep 16 '18 at 07:16
I was using AIDE app in android... it complied successful and showed me 33... — Muhammad Rokonuzzaman, Sep 16 '18 at 07:18
Maybe there is a bug in AIDE app... That's why it compiled... — Muhammad Rokonuzzaman, Sep 16 '18 at 07:22
I have successfully reproduced this on a oneplus 5 with AIDE v3.2.180516 on Android 8.1.0 — Matt, Sep 16 '18 at 07:49

score 4 · Accepted Answer · edited Jun 20 '20 at 09:12

If you can do this, it is a bug in the AIDE app. You should report it to the developers. A JLS compliant implementation of Java does not allow reassignment of final variables (like this).

If you want to give them a JLS specification reference to support your bug report:

JLS 4.12.4 final variables

A variable can be declared final. A final variable may only be assigned to once. It is a compile-time error if a final variable is assigned to unless it is definitely unassigned immediately prior to the assignment (§16 (Definite Assignment)).

Why can I re-assign a new value to a final variable in Android AIDE?

1 Answers1