Jakarta Commons Cookbook

2.14. Calculating String Difference

Problem

Your application needs to compare two strings and print out the difference.

Solution

Use StringUtils.difference( ), StringUtils.indexOfDifference( ), and StringUtils.getLevenshteinDistance( ). StringUtils.difference( ) prints out the difference between two strings, StringUtils.indexOfDifference( ) returns the index at which two strings begin to differ, and StringUtils.getLevenshteinDistance( ) returns the “edit distance” between two strings. The following example demonstrates all three of these methods:

int dist = StringUtils.getLevenshteinDistance( "Word", "World" );
String diff = StringUtils.difference( "Word", "World" );
int index = StringUtils.indexOfDifference( "Word", "World" );

System.out.println( "Edit Distance: " + dist );
System.out.println( "Difference: " + diff );
System.out.println( "Diff Index: " + index );

This code compares the strings “Word” and “World,” producing the following output:

Edit Distance: 2
Difference: ld
Diff Index: 3

Discussion

StringUtils.difference() returns the difference between two strings, returning the portion of the second string, which starts to differ from the first. StringUtils.indexOfDifference() returns the index at which the second string starts to diverge from the first. The difference between “ABC” and “ABE” is “E,” and the index of the difference is 2. Here’s a more complex example:

String a = "Strategy"; String b = "Strategic"; String difference = StringUtils.difference( a, b ); int differenceIndex ...