org.topoweb.util
Class StringComparator

java.lang.Object
  |
  +--org.topoweb.util.StringComparator

All Implemented Interfaces:

java.util.Comparator

public class StringComparator

extends java.lang.Object

implements java.util.Comparator

Comparator that uses the string representation of objects (Object.toString()). Additionally, the value null is taken to mean the largest possible value in this total ordering. This comparator works with all objects as every object has a toString() method.

Note: this comparator imposes orderings that are inconsistent with equals. The only situations where the ordering is consistent with equals is if for every pair of elements (a, b) in a set s of non-null elements, the expression a.toString().equals(b.toString()) implies that a.equals(b). The trivial case where the ordering is consistent with equals is when all the objects compared are Strings.

Author:

Babak Farhang

Constructor Summary

StringComparator()

Method Summary

int	compare(java.lang.Object a, java.lang.Object b) Compares the two objects a and b using their string representations.
boolean	equals(java.lang.Object other) Tests whether this instance is equal to another.

Methods inherited from class java.lang.Object

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

Constructor Detail

StringComparator

public StringComparator()

Method Detail

compare

public final int compare(java.lang.Object a,
                         java.lang.Object b)

Compares the two objects a and b using their string representations. Additionally, the value null for either of the arguments, represents the largest possible value. This method never throws an exception.

Specified by:

compare in interface java.util.Comparator

Parameters:

a - the first argument

b - the second argument

Returns:

• if either a or b is null:
  -1, if b is null but a is not; 0, if both a and b are null; 1, if a is null but b is not
• otherwise:
  a.toString().compareTo(b.toString())

equals

public final boolean equals(java.lang.Object other)

Tests whether this instance is equal to another.

Specified by:

equals in interface java.util.Comparator

Overrides:

equals in class java.lang.Object

Returns:

true, iff other is an instance of StringComparator