How to create an ArrayList method?

Okay so here are the requirements my teacher gave us.

Java Code:

 
/** 
 *The method creates an array list of integers and then prompts the user
 * for an integer.  As long as the user continues to enter anything other
 * than -999, add the number to the array list. 
 *
 * @return the array list of numbers
 */

I've attempted this several times but am still struggling. Can someone help?