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From: Lew <lewbloch@gmail.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: toward null-safe cookie cutter Comparators
Date: Sun, 20 Nov 2011 08:29:10 -0800 (PST)
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Wanja Gayk wrote:
> static <T> Comparator<T> nullLowComparator(final Comparator<T> delegate)
> {
>  return new Comparator<T>(){
>   public int compare(final T a, final T b){
>    return a != null && b != null ? delegate.compare(a,b) 
>         : a == null ? -1 
>         : 1;
>   }
>  }
> }

So if both 'a' and 'b' are both 'null', it returns -1?  That seems problematic - shouldn't it return 0?

I for one would expect 'null' to equal 'null'.

return a == b? 0 : a == null? -1 : b == null? 1 : delegate.compareTo(a, b);

The expression is a little easier if the type implements 'Comparable'.

-- 
Lew