string.trim() in java for string containing a lot of white spaces - its length is returned as 1 instead of 0

Question

The following code does not work as expected:

public int countSegments(String s) {
    System.out.println(Arrays.toString(s.trim().split(" ")));
    return (s.trim().split(" ")).length;
}

If s = " ", then ideally it should return 0. But it returns 1 even though the array printed is empty. Could anybody please explain how 1 is the result? Please note that s here contains multiple spaces, not just 1 space. StackOverflow is not allowing to enter multiple spaces.

Answer 1

split() of String returns new String[]{this} if no match is found. In your case, s.trim() returns "" and s.trim().split(" ") returns new String[]{""} . new String[]{""} is an array with 1 length. If you execute the expression System.out.println(s.trim().split(" ")[0].equals("")) you will get true