Checking for a not null, not blank String in Java

Question

I am trying to check if a Java String is not null, not empty and not whitespace.

In my mind, this code should have been quite up for the job.

Answer 1

With Java 8, you could also use the Optional capability with filtering. To check if a string is blank, the code is pure Java SE without additional library. The following code illustre a isBlank() implementation.

String.trim() behaviour

!Optional.ofNullable(tocheck).filter(e -> e != null && e.trim().length() > 0).isPresent()

StringUtils.isBlank() behaviour

Optional.ofNullable(toCheck)
    .filter(e -> 
        {
            int strLen;
            if (str == null || (strLen = str.length()) == 0) {
                return true;
            }
            for (int i = 0; i < strLen; i++) {
                if ((Character.isWhitespace(str.charAt(i)) == false)) {
                    return false;
                }
            }
            return true;

        })
    .isPresent()

Answer 2

You could take a look at JSR 303 Bean Validtion wich contains the Annotatinos @NotEmpty and @NotNull. Bean Validation is cool because you can seperate validation issues from the original intend of the method.