public static String join(String[] strings, String separator) {
        if (strings == null || strings.length == 0) {
            return EMPTY;
        }
        StringBuilder sb = new StringBuilder();
        for (String string : strings) {
            if (isNotBlank(string)) {
                sb.append(string).append(separator);
            }
        }
        return sb.length() > 0 ? sb.substring(0, sb.length() - separator.length()) : StringUtils.EMPTY;
    }
@Test
    public void testJoin() throws Exception {
        String[] src = new String[] { "1", "2", "3" };
        String arrayString = StringUtils.join(src, "");
        Assert.assertEquals(arrayString, "123");

        arrayString = StringUtils.join(src, ",");
        Assert.assertEquals(arrayString, "1,2,3");

        arrayString = StringUtils.join(new String[] {}, ",");
        Assert.assertEquals(arrayString, "");

        arrayString = StringUtils.join(null, "");
        Assert.assertEquals(arrayString, "");
    }