public static boolean isBlank(CharSequence str) {
        if ((str == null)) {
            return true;
        }
        int length = str.length();
        if (length == 0) {
            return true;
        }
        for (int i = 0; i < length; i++) {
            char c = str.charAt(i);
            boolean charNotBlank = Character.isWhitespace(c) || Character.isSpaceChar(c) || c == '\ufeff' || c == '\u202a';
            if (!charNotBlank) {
                return false;
            }
        }
        return true;
    }
@Test
    public void isBlank() {
        String string = "";
        Assert.assertTrue(StringUtil.isBlank(string));
    }