class StringUtil {

    /**
     * Compare version.
     *
     * versionA > versionB = 1
     * versionA == versionB = 0
     * versionA < versionB = -1
     *
     * @return  a negative integer, zero, or a positive integer as this object
     *          is less than, equal to, or greater than the specified object.
     */
    public static int versionCompare(String versionA, String versionB) throws NumberFormatException {
        if(Strings.isNullOrEmpty(versionA) || Strings.isNullOrEmpty(versionB))
            if (Strings.isNullOrEmpty(versionA))
                return Strings.isNullOrEmpty(versionB) ? 0 : -1;
            else
                return 1;

        String[] verA = versionA.split("\\.");
        String[] verB = versionB.split("\\.");

        for (int i = 0; i < verA.length; i++) {
            if(i >= verB.length)
                return 1;

            int a = Integer.parseInt(verA[i]);
            int b = Integer.parseInt(verB[i]);

            if(a == b) continue;
            return a < b ? -1 : 1;
        }

        return verA.length == verB.length ? 0 : -1;
    }

    @Test
    public void versionCompare() throws Exception {
        assertEquals(StringUtil.versionCompare(null, null), 0);
        assertEquals(StringUtil.versionCompare(null, "1.2"), -1);
        assertEquals(StringUtil.versionCompare("1.2", null), 1);
        assertEquals(StringUtil.versionCompare("", ""), 0);
        assertEquals(StringUtil.versionCompare(null, ""), 0);
        assertEquals(StringUtil.versionCompare("", null), 0);
        assertEquals(StringUtil.versionCompare(null, "ver"), -1);
        assertEquals(StringUtil.versionCompare("ver", null), 1);

        assertEquals(StringUtil.versionCompare("1.2", "1.1"), 1);
        assertEquals(StringUtil.versionCompare("1.2", "1.2"), 0);
        assertEquals(StringUtil.versionCompare("1.2", "1.3"), -1);

        assertEquals(StringUtil.versionCompare("1.2", "1.3.1"), -1);
        assertEquals(StringUtil.versionCompare("1.2", "1.2.1"), -1);
        assertEquals(StringUtil.versionCompare("1.2.1", "1.3"), -1);

        exception.expect(NumberFormatException.class);
        StringUtil.versionCompare("1.i.1", "1.3");

        exception.expect(NumberFormatException.class);
        StringUtil.versionCompare("versionA", "versionB");

        exception.expect(NumberFormatException.class);
        StringUtil.versionCompare("1-2-1", "1-3");
    }
}