Package org.apache.commons.collections.comparators

Class ReverseComparator

java.lang.Object
org.apache.commons.collections.comparators.ReverseComparator
All Implemented Interfaces:
Serializable, Comparator
public class ReverseComparator extends Object implements Comparator, Serializable
Reverses the order of another comparator by reversing the arguments to its compare method.
Since:
Commons Collections 2.0
Version:
$Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
Author:
Henri Yandell, Michael A. Smith
See Also:

  • 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().
      See Also:

    • 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 Collections.reverseOrder().
      Parameters:
      comparator - Comparator to reverse

  • Method Details

    • compare

      public int compare(Object obj1, Object obj2)
      Compares two objects in reverse order.
      Specified by:
      compare in interface Comparator
      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 Object
      Returns:
      a suitable hash code
      Since:
      Commons Collections 3.0

    • equals

      public boolean equals(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 Comparator
      Overrides:
      equals in class Object
      Parameters:
      object - the object to compare to
      Returns:
      true if equal
      Since:
      Commons Collections 3.0