public static Formatter forNumbers(@Nonnull String format) {
        return new NumberFormat(format);
    }
@Test
    public void testExponentialForm() {
        check(0,   " 0E+00",   "-0E+00",   "9EEEE");
        check(0,  " .0E+00",  "-.0E+00",  ".9EEEE");

        Formatter f = forNumbers("FM9.99EEEE");
        check(0,         f, "0E+00");
        check(5e4,       f, "5E+04");
        check(0.00045,   f, "4.5E-04");
        check(0.0004859, f, "4.86E-04");
    }