java program not compiling, issues with scope and lifetime of variables

Question

I am new to java. Could anyone explain why the following program not working? Thanks.

class AnonymousInnerClassInMethod
{
    public static void main(String[] args)
    {
        int local = 1;

        Comparable compare = new Comparable ()
        {
            public int compareTo(Object value)
            {
                return (Integer)value - local;
            }
        };
        System.out.println(compare.compareTo(5)); 
    }
}

Try with `final int local = 1;` (see http://stackoverflow.com/questions/1299837/cannot-refer-to-a-non-final-variable-inside-an-inner-class-defined-in-a-differen). — sp00m, Jun 20 '14 at 08:34
Please put more effort into formatting your code in future. Look at the preview of your post before you submit it, and ask yourself whether that's how *you'd* want to read it if you were trying to answer. — Jon Skeet, Jun 20 '14 at 08:35

score 0 · Answer 1 · edited May 23 '17 at 12:10

0

You either have to declare local as final:

final int local = 1;

(More information about this matter on this question, as suggested by sp00m).

Or define it as a static field of your class:

class AnonymousInnerClassInMethod {
    private static int local = 1;
    …
}

edited May 23 '17 at 12:10

Community

1
1

answered Jun 20 '14 at 08:37

arielnmz

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score 0 · Answer 2 · answered Jun 20 '14 at 08:39

First problem: You can't declare a public static void main(String[] args) inside a nested class, unless you mark that class as static as well.

Second problem: The anonymous constructor you use to define the compare's compareTo method cannot access the non-final variable local. This is an error, because the variable might change during/after construction of the object. Hence, if you mark it as final, it is ensured that the variable cannot change.

java program not compiling, issues with scope and lifetime of variables

2 Answers2