Source Code : Invertible Comparator

Java Is Open Source Programming Language You Can Download From Java and Java Libraries From http://www.oracle.com. Click Here to download
We provide this code related to title for you to solve your developing problem easily. Libraries which is import in this program you can download from http://www.oracle.com. Click Here or search from google with Libraries Name you get jar file related it

Invertible Comparator

    
import java.io.Serializable;
import java.util.Comparator;

/*
 * Copyright 2002-2005 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * A decorator for a comparator, with an "ascending" flag denoting
 * whether comparison results should be treated in forward (standard
 * ascending) order or flipped for reverse (descending) order.
 * 
 * @author Keith Donald
 * @author Juergen Hoeller
 * @since 1.2.2
 */
public class InvertibleComparator implements Comparator, Serializable {

  private final Comparator comparator;

  private boolean ascending = true;


  /**
   * Create an InvertibleComparator that sorts ascending by default.
   * For the actual comparison, the specified Comparator will be used.
   * @param comparator the comparator to decorate
   */
  public InvertibleComparator(Comparator comparator) {
    this.comparator = comparator;
  }

  /**
   * Create an InvertibleComparator that sorts based on the provided order.
   * For the actual comparison, the specified Comparator will be used.
   * @param comparator the comparator to decorate
   * @param ascending the sort order: ascending (true) or descending (false)
   */
  public InvertibleComparator(Comparator comparator, boolean ascending) {
    this.comparator = comparator;
    setAscending(ascending);
  }


  /**
   * Specify the sort order: ascending (true) or descending (false).
   */
  public void setAscending(boolean ascending) {
    this.ascending = ascending;
  }

  /**
   * Return the sort order: ascending (true) or descending (false).
   */
  public boolean isAscending() {
    return ascending;
  }

  /**
   * Invert the sort order: ascending -> descending or
   * descending -> ascending.
   */
  public void invertOrder() {
    this.ascending = !this.ascending;
  }


  public int compare(Object o1, Object o2) {
    int result = this.comparator.compare(o1, o2);
    if (result != 0) {
      // Invert the order if it is a reverse sort.
      if (!this.ascending) {
        if (Integer.MIN_VALUE == result) {
          result = Integer.MAX_VALUE;
        }
        else {
          result *= -1;
        }
      }
      return result;
    }
    return 0;
  }

  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (!(obj instanceof InvertibleComparator)) {
      return false;
    }
    InvertibleComparator other = (InvertibleComparator) obj;
    return (this.comparator.equals(other.comparator) && this.ascending == other.ascending);
  }

  public int hashCode() {
    return this.comparator.hashCode();
  }

  public String toString() {
    return "InvertibleComparator: [" + this.comparator + "]; ascending=" + this.ascending;
  }

}

   
    
    
    
  

Thank with us