Hamming Distance

/**
 * The Hamming distance between two strings of equal length is the number of positions
 * at which the corresponding symbols are different. In other words, it measures the
 * minimum number of substitutions required to change one string into the other.
 *
 * @author jdalbey
 * @version 0.1
 */
public class Hamming
{
    /**
     * Return the hamming distance between two strings.
     *
     * @param  alpha a string
     * @param  bravo a string
     * @pre alpha.length() == bravo.length();
     * @return number of positions at which corresponding characters differ
     */
    public static int getDistance(String alpha, String bravo)
    {
        int count = 0;
        // Iterate through all characters in both strings
        for (int pos = 0; pos < alpha.length(); pos++)
        {
            // If they don't match, increment the counter
            if (alpha.charAt(pos) != bravo.charAt(pos))
            {
                count++;
            }
        }
        return count;
    }
}


/**
 * The test class HammingDistanceTest.
 *
 * @author jdalbey
 * @version 0.1
 */
public class HammingDistanceTest extends junit.framework.TestCase
{

    public void testOne()
    {
        assertEquals(0, Hamming.getDistance("abc", "abc"));
        assertEquals(3, Hamming.getDistance("aaa", "bbb"));
        assertEquals(1, Hamming.getDistance("baa", "aaa"));
        assertEquals(1, Hamming.getDistance("aba", "aaa"));
        assertEquals(1, Hamming.getDistance("aab", "aaa"));
        assertEquals(2, Hamming.getDistance("bab", "aaa"));
    }
}