org.apache.commons.collections4.comparators

Class ReverseComparator<E>

java.lang.Object

org.apache.commons.collections4.comparators.ReverseComparator<E>

All Implemented Interfaces:

java.io.Serializable, java.util.Comparator<E>

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

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

Since:

2.0

See Also:

Collections.reverseOrder(), Serialized Form

Constructor Summary

Constructors

Constructor and Description
ReverseComparator() Creates a comparator that compares objects based on the inverse of their natural ordering.
ReverseComparator(java.util.Comparator<? super E> comparator) Creates a comparator that inverts the comparison of the given comparator.

Method Summary

Modifier and Type	Method and Description
int	compare(E obj1, E obj2) Compares two objects in reverse order.
boolean	equals(java.lang.Object object) 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.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Comparator

comparing, comparing, comparingDouble, comparingInt, comparingLong, naturalOrder, nullsFirst, nullsLast, reversed, reverseOrder, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Constructor Detail

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().

See Also:

Collections.reverseOrder()

ReverseComparator

public ReverseComparator(java.util.Comparator<? super E> 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 Collections.reverseOrder().

Parameters:

comparator - Comparator to reverse

Method Detail

compare

public int compare(E obj1,
                   E obj2)

Compares two objects in reverse order.

Specified by:

compare in interface java.util.Comparator<E>

Parameters:

obj1 - the first object to compare

obj2 - the second object to compare

Returns:

negative if obj1 is less, positive if greater, zero if equal

hashCode

public int hashCode()

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

Overrides:

hashCode in class java.lang.Object

Returns:

a suitable hash code

Since:

3.0

equals

public boolean equals(java.lang.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(), and the underlying comparators are equal. Subclasses may want to override this behavior to remain consistent with the equals contract.

Specified by:

equals in interface java.util.Comparator<E>

Overrides:

equals in class java.lang.Object

Parameters:

object - the object to compare to

Returns:

true if equal

Since:

3.0