String#split behavior when splitting the empty string according the "\s+"

Question

I am a newbie in Java. Unfortunately, in Java there is a lot of stuff that is very hard to understand to a newbie.

For example,

String str = "";
String[] arr = str.split("\\s+");
System.out.println(Arrays.toString(arr));
System.out.println(arr.length);
System.exit(0);

The output is

[]
1

But why? I will appreciate if someone can explain me why the length of the array is 1.

Answer 1

Even if the String instance is empty, it is still a String instance and the "nothing" must be put somewhere after split(). Thats the one element in the array.

If you printed str[0], you would get an empty string. The real "nothing" would be null but than you would get NullPointerException (you can't call split() on null value)