org.apache.commons.collections.comparators

Class ReverseComparator

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

All Implemented Interfaces:
Comparator, Serializable

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

Reverses the order of another comparator by reversing the arguments to its compare compare method.

Since:

Commons Collections 2.0

Authors:

Henri Yandell
Michael A. Smith

Constructor Summary

ReverseComparator()

Creates a comparator that compares objects based on the inverse of their natural ordering.

ReverseComparator(Comparator comparator)

Creates a comparator that inverts the comparison of the given comparator.

Method Summary

int

compare(Object o1, Object o2)

boolean

equals(Object that)

Returns true iff that Object is is a Comparator whose ordering is known to be equivalent to mine.

int

hashCode()

Implement a hash code for this comparator that is consistent with #equals.

Constructor Details

ReverseComparator

public ReverseComparator()

Creates a comparator that compares objects based on the inverse of their natural ordering. Using this Constructor will create a ReverseComparator that is functionally identical to the Comparator returned by java.util.Collections.reverseOrder().

ReverseComparator

public ReverseComparator(Comparator comparator)

Creates a comparator that inverts the comparison of the given comparator. If you pass in null, the ReverseComparator defaults to reversing the natural order, as per java.util.Collections.reverseOrder.

Parameters:

comparator - Comparator to reverse

Method Details

compare

public int compare(Object o1, Object o2)

Parameters:

o1
o2

equals

public boolean equals(Object that)

Returns true iff that Object is is a Comparator whose ordering is known to be equivalent to mine.

This implementation returns true iff that.Object.getClass getClass() equals this.getClass(), and the underlying comparators are equal. Subclasses may want to override this behavior to remain consistent with the Comparator.equals contract.

Since:

Commons Collections 3.0

Parameters:

that

hashCode

public int hashCode()

Implement a hash code for this comparator that is consistent with equals.

Since:

Commons Collections 3.0