edu.nrao.sss.sort
Class ReflectiveStringSortKey<T>

java.lang.Object
  edu.nrao.sss.sort.SortKey<String>
      edu.nrao.sss.sort.StringSortKey
          edu.nrao.sss.sort.ReflectiveStringSortKey<T>

All Implemented Interfaces:

Orderable, Comparator<T>

public final class ReflectiveStringSortKey<T>
extends StringSortKey
implements Comparator<T>

A sort key and comparator that works with the Strings returned by a method that is found reflectively.

Clients of this class must provide the name of a public, no argument, method that returns a String and that is present in classes of the parameterized type T. The method created from that name is called on the objects to be compared, and the strings returned from those methods are what is actually compared.

Because this class is a SortKey, you may configure its instances with a particular SortOrder. Because it is a StringSortKey, you may tell it to ignore differences in case. You may place instances of this class in a CompoundComparator.

Example
Let there be a class, PostalAddress, that has the following attributes, each of which is a String: state, city, postalCode. Furthermore, assume the normal convention for the getters (e.g., getCity()). You could sort a collection of addresses by state, then city, then postal code, without writing any new classes by doing this:

   ReflectiveStringSortKey<Address> stateKey =
     new ReflectiveStringSortKey<Address>("getState");
     
   ReflectiveStringSortKey<Address> cityKey =
     new ReflectiveStringSortKey<Address>("getCity");
     
   ReflectiveStringSortKey<Address> codeKey =
     new ReflectiveStringSortKey<Address>("getPostalCode");
     
   CompoundComparator<Address> comparator =
     new CompoundComparator<Address>(stateKey, cityKey, codeKey);
     
   Collections.sort(myAddresses, comparator);
 

Version Info:

$Revision: 593 $

$Date: 2007-05-07 15:54:14 -0600 (Mon, 07 May 2007) $

$Author: dharland $

Since:

2007-05-04

Author:

David M. Harland

Constructor Summary

ReflectiveStringSortKey(String methodName)
Creates a new instance that will base its comparison on the String returned by the method with the given name.

Method Summary

int	compare(T o1, T o2)
void	setMethodName(String newMethodName) Sets the name of the method used for making comparisons.

Methods inherited from class edu.nrao.sss.sort.StringSortKey

compareAscending, compareNatural, setIgnoreCase

Methods inherited from class edu.nrao.sss.sort.SortKey

compareObjects, compareObjects, getOrder, nullOrdering, objectsAreEqual, setOrder

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals

Constructor Detail

ReflectiveStringSortKey

public ReflectiveStringSortKey(String methodName)

Creates a new instance that will base its comparison on the String returned by the method with the given name.

Parameters:

methodName - the name of a public, no argument, method that belongs to objects of type T and that returns a String. If there is any trouble creating or calling the method with this name, it will be treated as if it returns a String of null.

Method Detail

setMethodName

public void setMethodName(String newMethodName)

Sets the name of the method used for making comparisons.

Parameters:

newMethodName - the name of a public, no argument, method that belongs to objects of type T and that returns a String. If there is any trouble creating or calling the method with this name, it will be treated as if it returns a String of null.

compare

public int compare(T o1,
                   T o2)

Specified by:

compare in interface Comparator<T>