Question

I have a list of words sorted using g_ascii_strcasecmp function. I need to process this list in java. What is the equivalent sorting function in java? In order to implement binary search I need a correct comparison function. So far I have the function below but it is not always produces the correct result.

public int compareStrings(String str) {
    Collator collator = Collator.getInstance();//TODO: implement locale?
    return collator.compare(this.wordString, str);
}

UPDATE. List example: “T, t, T’ai Chi Ch’uan, t’other, T-, T-bone, T-bone steak, T-junction, tabasco, Tabassaran, tabby”.

Answer 1

I decided to share the method I came up with:

    /**
     * Compares two strings, ignoring the case of ASCII characters. It treats
     * non-ASCII characters taking in account case differences. This is an 
     * attempt to mimic glib's string utility function 
     * <a href="http://developer.gnome.org/glib/2.28/glib-String-Utility-Functions.html#g-ascii-strcasecmp">g_ascii_strcasecmp ()</a>.
     *
     * This is a slightly modified version of java.lang.String.CASE_INSENSITIVE_ORDER.compare(String s1, String s2) method.
     * 
     * @param str1  string to compare with str2
     * @param str2  string to compare with str1
     * @return      0 if the strings match, a negative value if str1 < str2, or a positive value if str1 > str2
     */
    private static int compareToIgnoreCaseASCIIOnly(String str1, String str2) {
        int n1 = str1.length();
        int n2 = str2.length();
        int min = Math.min(n1, n2);
        for (int i = 0; i < min; i++) {
            char c1 = str1.charAt(i);
            char c2 = str2.charAt(i);
            if (c1 != c2) {
                if ((int) c1 > 127 || (int) c2 > 127) { //if non-ASCII char
                    return c1 - c2;
                } else {
                    c1 = Character.toUpperCase(c1);
                    c2 = Character.toUpperCase(c2);
                    if(c1 != c2) {
                        c1 = Character.toLowerCase(c1);
                        c2 = Character.toLowerCase(c2);
                        if(c1 != c2) {
                            return c1 - c2;
                        }
                    }
                }
            }
        }
        return n1 - n2;
    }