Java ArrayList size with empty element []

Question

I have one ArrayList, for some reason i have to add empty string element "":

ArrayList<String> rList = new ArrayList<String>();
rList.add("");

When I read the size of the array list rList then, rList.size() == 1 and rList.isEmpty() == false.

How can I check this kind of array list? does the empty element cause the size equals 1 and not empty?

Answer 1

Even though you're adding an empty string to your list, you're still adding something to the list. And, that's what counts.

The data may be empty (or even null, as an ArrayList will allow you to insert null), but the size will increase (and the list won't be empty).

Now, if you only want to check that there's just that sort of element in your list (as you state in comments), then that's possible like this:

if(rList.size() == 1 && "".equals(rList.get(0)) {
    // perform work
}

The line above will only succeed if there's just one entry in the list, and only if it's the empty string. The reverse of the string literal and get is to guard against a NullPointerException, as that can occur if you have it flipped the other way 'round, and there's null in for element 0.