比较Java中对象的更优雅方法

Question

Java has an inteface Comparator<T> , that has a method int compare(T o1, T o2) .

EDIT:

I was wrong with this:

The returned integer must be -1 if the first object is less than second one, 1 if second one is less than first one, 0 if they're equal.

Docs state:

a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

So I rephrase my question: Is there a more elegant way of comparing objects, than bearing in mind that comparator.compare(o1, o2) < 0 actually means that first object is less than second one?

Answer 1

Compare your statement

The returned integer must be -1 if the first object is less than second one, 1 if second one is less than first one, 0 if they're equal.

with the official statement

Returns a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

and note that the only appropriate constant is zero.

Answer 2

The official interface contract for compare method is:

Returns a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

While in fact all you need is three values, this logic can be used to write elegant code like this:

public int compare(MyObject o1, MyObject o2){
    return o1.getIntValue() - o2.getIntValue();
}

Which in one line not only gives you which object is greater (or equal), it even gives you how much one is greater than the other.

(Integer overflows not considered.)