org.kuali.kra.util

Class NaturalStringComparator

java.lang.Object

org.kuali.kra.util.NaturalStringComparator

All Implemented Interfaces:

Serializable, Comparator<String>

public class NaturalStringComparator
extends Object
implements Serializable, Comparator<String>

This class provides a method of comparing Strings that results is a more natural ordering than the default ordering outlined by the Java Specification. This method takes into account the numeric ordering of both initial and internal strings of digits. For instance, using the list {"10", "5", "20"} as an example, Java's default comparison would sort it as {"10", "20", "5"} whereas this comparator will sort it as {"5", "10", "20"}. As a second example, consider the list {"file200.txt", "file1.txt", "file80.txt"}. The default Java behavior would be to sort the list as {"file1.txt", "file200.txt", "file80.txt"} while this comparator will sort the list as {"file1.txt", "file80.txt", "file200.txt"}.

Some important things to note:

• This comparator makes no allowances for negative numbers, the '-' will be interpreted as a non-numeric character
• The same is true for the '.' and ',' characters. Decimals and number groupings are not supported.
• This comparator uses a long to process each numeric String segment. As such, the maximum number portion processable by this comparator is 2^63 - 1 or 9,223,372,036,854,775,807 (without the commas, of course).
• This comparator is mostly case-insensitive. The only time case is considered is in the case where two strings are identical in every respect except case. In that situation the standard Java ordering applies.
• This comparator treats null as the lowest possible String followed by the empty string ("") followed by all other Strings.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
NaturalStringComparator()

Method Summary

Methods

Modifier and Type	Method and Description
int	compare(String string1, String string2) Compares its two arguments for order.
static NaturalStringComparator	getInstance()

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

NaturalStringComparator

public NaturalStringComparator()

Method Detail

getInstance

public static NaturalStringComparator getInstance()

compare

public int compare(String string1,
          String string2)

Compares its two arguments for order. Returns a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

Uses the more natural ordering of Strings defined by this class.

Specified by:

compare in interface Comparator<String>

Parameters:

string1 - the first String to be compared

string2 - the second String to be compared

Returns:

a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second

See Also:

Comparator.compare(java.lang.Object, java.lang.Object)