code: public int indexOf( T obj ) {
  		for (int i = 0; i < size; i++) {
  			if( data[i].equals(obj) ) {
  				return i;
  			}
  		}
  		return -1;
  	}
docs: Returns the first index which equals() obj. -1 is there is no match
  
  @param obj The object being searched for
  @return index or -1 if not found