orbital.util
Class ReverseComparator

java.lang.Object
  orbital.util.ReverseComparator

All Implemented Interfaces:

java.io.Serializable, java.util.Comparator

public class ReverseComparator
extends java.lang.Object
implements java.util.Comparator, java.io.Serializable

This class is a ReverseComparator which imposes the reverse order on a collection of objects.

Depending on whether a Comparator to be reverted is given, the ordering induced by that Comparator will be reverted. Otherwise, the natural ordering will be reverted - as Collections.revertOrder() does - supposing that the objects in the collection implement the Comparable interface.

This corresponds roughly to a negation of a comparator (except for the case of equality).

Author:

André Platzer

See Also:

Collections.reverseOrder(), Serialized Form

Field Summary

protected java.util.Comparator

inner Contains the Comparator to be inverted, or null if the objects Comparable implementation should be used, instead.

Constructor Summary

ReverseComparator()
Create a Comparator that is the opposite to the natural ordering induced by the Comparable implementation of the objects compared.

ReverseComparator(java.util.Comparator inner)
Create a Comparator that is the opposite to an ordering induced by a given one.

Method Summary

int	compare(java.lang.Object o1, java.lang.Object o2) Compares two objects.
boolean	equals(java.lang.Object obj)
int	hashCode()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

inner

protected java.util.Comparator inner

Contains the Comparator to be inverted, or null if the objects Comparable implementation should be used, instead.

Constructor Detail

ReverseComparator

public ReverseComparator(java.util.Comparator inner)

Create a Comparator that is the opposite to an ordering induced by a given one.

Parameters:

inner - the Comparator to be inverted, or null if the objects Comparable implementation should be used, instead.

ReverseComparator

public ReverseComparator()

Create a Comparator that is the opposite to the natural ordering induced by the Comparable implementation of the objects compared.

Method Detail

compare

public int compare(java.lang.Object o1,
                   java.lang.Object o2)

Compares two objects. The inner Comparator is used if specified, or one of the arguments are used if they implement Comparable.

Specified by:

compare in interface java.util.Comparator

Returns:

If a Comparator inner!=null, then this method returns inner.compare(o2,o1). If inner==null and if one of the objects (preferably o1) is Comparable, -((Comparable)on).compareTo(om) is returned. If no comparator is specified and none of the objects implements Comparable, an exception is thrown.

Throws:

java.lang.ClassCastException - if Comparator inner==null and both, o1 and o2 do not implement Comparable.

equals

public boolean equals(java.lang.Object obj)

Specified by:

equals in interface java.util.Comparator

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object