I think the point is that he needed a comparison function not and equals function. thus the subtraction. Erric Lippert had a nice series on subtle bugs in co

I think the point is that he needed a comparison function not and equals function. thus the subtraction. Erric Lippert had a nice series on subtle bugs in compareTo implementations, in part3 he talks about a similar version of this bug. http://blogs.msdn.com/b/ericlippert/archive/2011/01/27/spot-the-defect-bad-comparisons-part-three.aspx http://blogs.msdn.com/b/ericlippert/archive/2011/01/27/spot-... tldr; if you aren't doing a comparison in your compareTo implementation, you probably have a bug.