why can't I write the using reverse method.

public static void main(String[] args) throws Exception {
     // Read strings from the console and declare an ArrayList here

     BufferedReader reader = new BufferedReader (new InputStreamReader(System.in));

     ArrayList<String> list = new ArrayList<String>();

     for(int i = 0 ; i<5;i++){

         list.add(reader.readLine());

     }

     ArrayList<String> result = doubleValues(list);

     // Display result
     for(String sd : result){
         System.out.println(sd);
     }
 }

 public static ArrayList<String> doubleValues(ArrayList<String> list) {
     //write your code here

     ArrayList<String> reversal = new ArrayList<String>(reverse(list));

     list.addAll(reversal);

  /*   for(int i = list.size()-1 ; i > -1; i--) {
         list.add(i, list.get(i));
     }
   */
     return list;
 }

 }