Best way to verify string is empty or null

Question

i am sure this must have been asked before in different ways - as isEmptyOrNull is so common yet people implement it differently. but i have below curious query in terms of

Answer 1

In most of the cases, StringUtils.isBlank(str) from apache commons library would solve it. But if there is case, where input string being checked has null value within quotes, it fails to check such cases.

Take an example where I have an input object which was converted into string using String.valueOf(obj) API. In case obj reference is null, String.valueOf returns "null" instead of null.

When you attempt to use, StringUtils.isBlank("null"), API fails miserably, you may have to check for such use cases as well to make sure your validation is proper.