Queue

Many structures are built into a standard Java libraries, so we can just call them.
The queue is typical example:

public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      Queue qq = new Queue();
      qq.addLast(5);
      qq.addLast(7);
      qq.addLast(3);
      //====================================================
      int x;
      do {
      System.out.println(qq.toString());
      System.out.print("1-add,2-erase,9-end: ");
      x = sc.nextInt();
      if (x==1) {
        System.out.print("Enter value: ");
        int i = sc.nextInt();
        qq.addLast(i);
        System.out.println();
      }
      if (x==2) {
        int i = qq.deteteFirst();
        System.out.print("Erased value: ");
        System.out.println(i);
      }
      } while (x != 9);
      System.out.print("Exiting.");
    }
}