Hello guys, nice to meet you all. I was looking forward to a solution to fix the problem that makes my algorithm die. It is about a linked-list, the elements are type Node which contains a integer, which represents the priority of the node.
I wanted to sort the given input based on the int inside the node by sort-selection.

Code:
package partial1;

import java.util.StringTokenizer;

class Node {

    int v;
    public Node next;
   

    public Node(int val) {
        this.v = val;
    }

    public String show() {
        return " " + this.v;
    }

    public int valoare() {
        return v;
    }
}

public class Partial1 {

    public Partial1(String secv) {

        StringTokenizer st = new StringTokenizer(secv);
        Node t = new Node(Integer.parseInt(st.nextToken())); //head
        Node k = t;


        while (st.hasMoreTokens()) {
            int v = Integer.parseInt(st.nextToken());
            k.next = new Node(v);
            k = k.next;
        }
        k.next = null;


        k = t;

        Node j = k.next;
        Node temp;

        while (k.next != null) {
            while (j.next != null) {

                if (k.valoare() < j.valoare()) {
                    temp = k.next;
                    k.next = j.next;
                    j.next = temp;

                }
                j = j.next;
            }

            k = k.next;

        }

        k = t;

        while (k != null) {
            System.out.print("node= " + k.show() + "\n");
            k = k.next;
        }
    }

    public static void main(String[] args) {
        Partial1 k = new Partial1("3 6 9 4 12 15");
    }
}
The result is: 3 4 9 12 6 15