Java Cookbook

Program: Soundex Name Comparisons

The difficulties in comparing (American-style) names inspired the development of the Soundex algorithm, in which each of a given set of consonants maps to a particular number. This was apparently devised for use by the Census Bureau to map similar-sounding names together on the grounds that in those days many people were illiterate and could not spell their parents’ names correctly. But it is still useful today: for example, in a company-wide telephone book application. The names Darwin and Derwin, for example, map to D650, and Darwent maps to D653, which puts it adjacent to D650. All of these are historical variants of the same name. Suppose we needed to sort lines containing these names together: if we could output the Soundex numbers at the front of each line, this would be easy. Here is a simple demonstration of the Soundex class:

/** Simple demonstration of Soundex.  */
public class SoundexSimple {

    /** main */
    public static void main(String[] args) { 
        String[] names = {
            "Darwin, Ian",
            "Davidson, Greg",
            "Darwent, William",
            "Derwin, Daemon"
        };
        for (int i = 0; i< names.length; i++)
            System.out.println(Soundex.soundex(names[i]) + ' ' + names[i]);
    }
}

Let’s run it:

> jikes +E -d . SoundexSimple.java
> java SoundexSimple | sort
D132 Davidson, Greg
D650 Darwin, Ian
D650 Derwin, Daemon
D653 Darwent, William
>

As you can see, the Darwin-variant names (including Daemon Derwin^[13]) all sort together and are distinct from the Davidson (and Davis, Davies, etc.) ...