Class ComparableComparator<E extends Comparable<? super E>>
- Type Parameters:
E
- the type of objects compared by this comparator
- All Implemented Interfaces:
Serializable
,Comparator<E>
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.
- Since:
- 2.0
- See Also:
-
Field Summary
Fields -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionstatic <E extends Comparable<? super E>>
ComparableComparator<E>Gets the singleton instance of a ComparableComparator.int
Compare the twoComparable
arguments.boolean
Returnstrue
iff that Object is is aComparator
whose ordering is known to be equivalent to mine.int
hashCode()
Implement a hash code for this comparator that is consistent withequals
.
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Field Details
-
INSTANCE
The singleton instance.
-
-
Constructor Details
-
ComparableComparator
public ComparableComparator()Constructor whose use should be avoided.Please use the
comparableComparator()
method whenever possible.
-
-
Method Details
-
comparableComparator
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.
- Type Parameters:
E
- the element type- Returns:
- the singleton ComparableComparator
- Since:
- 4.0
-
compare
Compare the twoComparable
arguments. This method is equivalent to:((Comparable)obj1).compareTo(obj2)
- Specified by:
compare
in interfaceComparator<E extends Comparable<? super E>>
- Parameters:
obj1
- the first object to compareobj2
- the second object to compare- Returns:
- negative if obj1 is less, positive if greater, zero if equal
- Throws:
NullPointerException
- if obj1 isnull
, or when((Comparable)obj1).compareTo(obj2)
doesClassCastException
- if obj1 is not aComparable
, or when((Comparable)obj1).compareTo(obj2)
does
-
hashCode
Implement a hash code for this comparator that is consistent withequals
. -
equals
Returnstrue
iff that Object is is aComparator
whose ordering is known to be equivalent to mine.This implementation returns
true
iffobject.
equalsgetClass()
this.getClass()
. Subclasses may want to override this behavior to remain consistent with theComparator.equals(Object)
contract.- Specified by:
equals
in interfaceComparator<E extends Comparable<? super E>>
- Overrides:
equals
in classObject
- Parameters:
object
- the object to compare with- Returns:
true
if equal- Since:
- 3.0
-