public interface java.util.Comparator<A>

java.lang.Object
   |
   +----java.util.Comparator<A>

public interface Comparator<A>

A comparison function, which imposes a total ordering on some collection of Objects. Comparators can be passed to a sort method (such as Arrays.sort) to allow precise control over the sort order. Comparators can also be used to control the order of certain data structures (such as TreeMap).

See also:

java.lang.Comparable, sort(Object[], Comparator), TreeMap

compare(A, A)

Compares its two arguments for order

public abstract int compare(A o1,
                            A o2);

Compares its two arguments for order. Returns a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

The implementor must ensure that sgn(compare(x, y)) == -sgn(compare(y, x)) for all x and y. (This implies that compare(x, y) must throw an exception if and only if compare(y, x) throws an exception.)

The implementor must also ensure that the relation is transitive: ((compare(x, y)>0) && (compare(y, z)>0)) implies compare(x, z)>0.

The implementer must also ensure that x.equals(y) implies that compare(x, y) == 0. Note that the converse is not necessarily true.

Finally, the implementer must ensure that compare(x, y) == 0 implies that sgn(compare(x, z)) == sgn(compare(y, z)), for all z.

Returns:

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

Throws:

ClassCastException -the arguments' types prevent them from being compared by this Comparator.

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