Soundex.java

/* The main principle behind Soundex algorithm is that consonants are grouped depending on the ordinal numbers and
finally encoded into a value against which others are matched. 
It aims to find a code for every word by above process which is called soundex code.
*/



public class Soundex {
    public static String getGode(String s) 
    {
        char[] x = s.toUpperCase().toCharArray();
         
         
        char firstLetter = x[0];
 
        //RULE [ 2 ]
        //Convert letters to numeric code
        for (int i = 0; i < x.length; i++) {
            switch (x[i]) {
            case 'B':
            case 'F':
            case 'P':
            case 'V': {
                x[i] = '1';
                break;
            }
 
            case 'C':
            case 'G':
            case 'J':
            case 'K':
            case 'Q':
            case 'S':
            case 'X':
            case 'Z': {
                x[i] = '2';
                break;
            }
 
            case 'D':
            case 'T': {
                x[i] = '3';
                break;
            }
 
            case 'L': {
                x[i] = '4';
                break;
            }
 
            case 'M':
            case 'N': {
                x[i] = '5';
                break;
            }
 
            case 'R': {
                x[i] = '6';
                break;
            }
 
            default: {
                x[i] = '0';
                break;
            }
            }
        }
 
        //Remove duplicates
        //RULE [ 1 ]
        String output = "" + firstLetter;
         
        //RULE [ 3 ]
        for (int i = 1; i < x.length; i++)
            if (x[i] != x[i - 1] && x[i] != '0')
                output += x[i];
 
        //RULE [ 4 ]
        //Pad with 0's or truncate
        output = output + "0000";
        return output.substring(0, 4);
    }

    public static void main(String[] args) 
    {
        String name1 = "Tail";
        String name2 = "Tale";
        String name3 = "Tailor";
         
        System.out.println(Soundex.getGode(name1));
        System.out.println(Soundex.getGode(name2));
        System.out.println(Soundex.getGode(name3));
    }
}

/*
t is clear from above output that words “tail” and “tale” have same code.
Hence they are phonetic. 
Word “tailor” has different code because it’s not phonetic same.
*/