Strings { public static boolean isBlank(CharSequence string) { return string == null || string.toString().trim().length() == 0; } private  Strings(); static boolean isBlank(CharSequence string);  }
@Test public void nullIsBlank() { assertThat(Strings.isBlank(null), is(true)); }
@Test public void emptyIsBlank() { assertThat(Strings.isBlank(""), is(true)); }
@Test public void spaceIsBlank() { assertThat(Strings.isBlank(" "), is(true)); }
@Test public void stringIsNotBlank() { assertThat(Strings.isBlank("not blank "), is(false)); }