oracle.jbo.server.java.util
Interface Comparator

public interface Comparator

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).

Since:

JDK1.2

See Also:

Comparable, Arrays.sort(Object[], Comparator), TreeMap

Method Summary

int	compare(java.lang.Object o1, java.lang.Object o2) Compares its two arguments for order.

Method Detail

compare

public int compare(java.lang.Object o1,
                   java.lang.Object 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:

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

Since:

JDK1.2