Ok, yeah, so it is kind of like a permutation of the numbers.
So, think of the base case and recursive case. So the base case is when there is 1 value left, and the recursive case takes out one of...

You want to use a StringTokenizer. So and them together.
So:

String head = "47 23 2 5 98";
String returnHead = "";
StringTokenizer s = new StringTokenizer(head, " ");
while(s.hasNextToken()){...