How to Annotate an Array NonNull?

Question

I'm using org.eclipse.jdt.annotation.NonNull to add extra information for static null analysis. I donn't know how to annotate arrays correctly:

How can I say that an array reference is non-null?
How can I say that an array consists of non-null elements?

I've tested:

    public static void test(@NonNull String[] a) {
        assert a != null;
    }

    public static void main(String[] args) {
        test(null);
    }

However, Eclipse doesn't mark test(null); as wrong.

Nathan · Accepted Answer · 2016-11-03 12:34:48Z

15

If you 're using Java 8, it looks as follows:

@NonNull Object [] o1;

o1    = null;           // OK
o1    = new Object[1];
o1[0] = null;           // NOT OK

Object @NonNull[] o2;

o2    = null;           // NOT OK
o2    = new Object[1];
o2[0] = null;           // OK

edited Nov 3, 2016 at 12:34

Nathan

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answered Mar 12, 2015 at 14:13

René Winkler

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KrishPrabakar · Accepted Answer · 2015-03-13 05:00:49Z

5

How can I say that an array reference is non-null?

You should've put @NonNull after the type declaration (but before the array brackets), eg.,

public static void test(String @NonNull[] a) {
    assert a != null;
}

How can I say that an array consists of non-null elements?

Your original question has that.

EDIT: For Java 8 compatibility, the syntax had to be changed a little (modified above code accordingly).

edited Mar 13, 2015 at 5:00

answered Mar 12, 2015 at 14:22

KrishPrabakar

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