Link list problem

Question

I have one link list class. Each record holds only one data.
Now I am going to modify it. Each record holds two real numbers.
how to do it?
Thanks
class ListNode
   // package access members; List can access these directly
   Object data;   
   ListNode nextNode;
   // constructor creates a ListNode that refers to object
   ListNode( Object object )
      this( object, null );
   } // end ListNode one-argument constructor
   // constructor creates ListNode that refers to
   // Object and to next ListNode
   ListNode( Object object, ListNode node )
      data = object;   
      nextNode = node; 
   } // end ListNode two-argument constructor
   // return reference to data in node
   Object getObject()
      return data; // return Object in this node
   } // end method getObject
   // return reference to next node in list
   ListNode getNext()
      return nextNode; // get next node
   } // end method getNext
} // end class ListNode
// class List definition
public class List
   private ListNode firstNode;
   private ListNode lastNode;
   private String name; // string like "list" used in printing
   // constructor creates empty List with "list" as the name
   public List()
      this( "list" );
   } // end List no-argument constructor
   // constructor creates an empty List with a name
   public List( String listName )
      name = listName;
      firstNode = lastNode = null;
   } // end List one-argument constructor
   // insert Object at front of List
   public void insertAtFront( Object insertItem )
      if ( isEmpty() ) // firstNode and lastNode refer to same object
         firstNode = lastNode = new ListNode( insertItem );
      else // firstNode refers to new node
         firstNode = new ListNode( insertItem, firstNode );
   } // end method insertAtFront
public static void main( String args[])
             List list1 = new List();
             int array1[] = { 160, 591, 114, 229, 230, 270, 128, 1657, 624, 1503 };
                                     //insert numbers in list
             for (int c1 = 0; c1 < array1.length; c1++ )
                 list1.insertAtFront(array1[ c1 ]);
...

Answer 1

ok, there we go.
I modified a little.
I added a class.
public class data
    private double x;
    private double y;
    public data(double x,double y)
    x=this.x;
    y=this.y;
}in main program
public static void main( String args[] )
      List list = new List(); // create the List container
      data x1 =new data(9,-9);
      list.insertAtFront( x1 );
      list.print();
      data x2 =new data(8,-8);
      list.insertAtFront( x2 );
      list.print();
      data x3 =new data(7,-7);
      list.insertAtBack( x3 );
      list.print();
      data x4 =new data(6,-6);
      list.insertAtBack( x4 );
      list.print();
...Do I need change print method, some errors occuried.
public void print()
      if ( isEmpty() )
         System.out.printf( "Empty %s\n", name );
         return;
      } // end if
      System.out.printf( "The %s is: ", name );
      ListNode current = firstNode;
      // while not at end of list, output current node's data
      while ( current != null )
         System.out.printf( "%s ", current.data );
         current = current.nextNode;
      } // end while
      System.out.println( "\n" );
   } // end method print
} // end class List