Can't see why I can't compile this

Question

I can't seem to compile this code, and yet its supposed to because this is how our professor gave it to us on the website. Can anyone tell me what I need to make it compile? Thanks in advance.
ArrayList list = new ArrayList(5);
list.add(0, new Object());
list.add(new Object());
Object object = list.remove(1);
ArrayList<Player> players = new ArrayList<Player>(10);
class Player implements Comparable<Player> {
  public int compareTo(Player player) {
class PlayerNameComparator implements Comparator<Player> {
  public int compare(Player player1, Player player2) {
class MyStack {
  public int tos;
  public Comparable list[];
  // public ArrayList<Player> list;
  public MyStack() {
    tos = 0;
    list = new Comparable[10];
  public Comparable pop() {
    tos--;
    Comparable comparable = list[tos];
    list[tos] = null;
    return comparable;
  public void push(Comparable element) {
    list[tos] = element;
    tos++;
  public String toString() {
    String data = new String();
    MyStack temp = new MyStack();
    Comparable element = null;
    while (this.tos > 0) {
      element = this.pop();
      temp.push(element);
      data = data + element.toString();
    while (temp.tos > 0) {
      this.push(temp.pop());
}

Answer 1

The compiler always produces helpful messages which describe why text won't compile. If you can't understand them it would be a good idea to post those compiler messages.