org.apache.commons.collections.comparators

Class ComparableComparator

java.lang.Object
|
+--org.apache.commons.collections.comparators.ComparableComparator

All Implemented Interfaces:
Comparator, Serializable

public class ComparableComparator
extends java.lang.Object
implements Comparator, Serializable

A Comparator Comparator that compares Comparable 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 compare were null, not Comparable Comparable, or for which Comparable.compareTo compareTo gave inconsistent results. This is no longer the case. See compare for details.

Since:

Commons Collections 2.0

Author:

Henri Yandell

Constructor Summary

ComparableComparator()

Method Summary

int	compare(Object o1, Object o2) Compare the two Comparable Comparable arguments.
boolean	equals(Object that) Returns true iff that Object is is a Comparator Comparator whose ordering is known to be equivalent to mine.
static ComparableComparator	getInstance() Return a shared instance of a ComparableComparator.
int	hashCode() Implement a hash code for this comparator that is consistent with #equals.

Constructor Details

ComparableComparator

public ComparableComparator()

Method Details

compare

public int compare(Object o1, Object o2)

Compare the two Comparable Comparable arguments. This method is equivalent to:

((

Comparable Comparable)o1).Comparable.compareTo compareTo(o2)

Parameters:

o1
o2

Throws:

- when o1 is null, or when ((Comparable)o1).compareTo(o2) does
- when o1 is not a Comparable Comparable, or when ((Comparable)o1).compareTo(o2) does

equals
public boolean equals(Object that)
 Returns true iff that Object is 
 is a Comparator Comparator whose ordering is 
 known to be equivalent to mine.
 
 This implementation returns true
 iff that.Object.getClass getClass()
 equals this.getClass().  Subclasses may want to override
 this behavior to remain consistent with the Comparator.equals
 contract.
Since:
Commons Collections 3.0
Parameters:
that
getInstance
public static ComparableComparator getInstance()
  Return a shared 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.
hashCode
public int hashCode() Implement a hash code for this comparator that is consistent with
equals.
Since:
Commons Collections 3.0
Returns:
a hash code for this comparator.
Generated on
  February 15, 2004
  by GNU Classpath Tools (Gjdoc XmlDoclet 0.6.1).