org.apache.commons.collections.comparators
Class ComparableComparator
java.lang.Object
org.apache.commons.collections.comparators.ComparableComparator
- Comparator, Serializable
public class ComparableComparator
extends java.lang.Object
implements Comparator, Serializable
A
Comparator
that compares
Comparable
objects.
This Comparator is useful, for example,
for enforcing the natural order in custom implementations
of SortedSet and SortedMap.
Note: In the 2.0 and 2.1 releases of Commons Collections,
this class would throw a
ClassCastException
if
either of the arguments to
compare
were
null
, not
Comparable
,
or for which
compareTo
gave
inconsistent results. This is no longer the case. See
compare
for details.
$Revision: 1.15 $ $Date: 2004/05/15 13:24:11 $java.util.Collections.reverseOrder()
int | compare(Object obj1, Object obj2) - Compare the two
Comparable arguments.
|
boolean | equals(Object object) - Returns
true iff that Object is
is a Comparator whose ordering is
known to be equivalent to mine.
|
static ComparableComparator | getInstance() - Gets the singleton instance of a ComparableComparator.
|
int | hashCode() - Implement a hash code for this comparator that is consistent with
equals .
|
ComparableComparator
public ComparableComparator()
Constructor whose use should be avoided.
Please use the
getInstance()
method whenever possible.
compare
public int compare(Object obj1,
Object obj2)
Compare the two
Comparable
arguments.
This method is equivalent to:
((Comparable)obj1).compareTo(obj2)
obj1
- the first object to compareobj2
- the second object to compare
- negative if obj1 is less, positive if greater, zero if equal
equals
public boolean equals(Object object)
Returns
true
iff
that Object is
is a
Comparator
whose ordering is
known to be equivalent to mine.
This implementation returns
true
iff
object.getClass()
equals
this.getClass()
.
Subclasses may want to override this behavior to remain consistent
with the
Comparator.equals(Object)
contract.
object
- the object to compare with
getInstance
public static ComparableComparator getInstance()
Gets the singleton instance of a ComparableComparator.
Developers are encouraged to use the comparator returned from this method
instead of constructing a new instance to reduce allocation and GC overhead
when multiple comparable comparators may be used in the same VM.
- the singleton ComparableComparator
hashCode
public int hashCode()
Implement a hash code for this comparator that is consistent with
equals
.
- a hash code for this comparator.
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