data thelist deletefirst(the user of the stack class calls push(and pop(to insert and delete itemswithout knowingor needing to knowwhether the stack is implemented as an array or as linked list listing shows how stack class called linkstack can be implemented using the linklist class instead of an array (object purists would argue that the name linkstack should be simply stackbecause users of this class shouldn' need to know that it' implemented as list listing the linkstack(program /linkstack java /demonstrates stack implemented as list /to run this programc>java linkstackapp import java io */for / ///////////////////////////////////////////////////////////////class link public double ddata/data item public link next/next link in list /public link(double dd/constructor ddata dd/public void displaylink(/display ourself system out print(ddata ")/end class link ///////////////////////////////////////////////////////////////class linklist private link first/ref to first item on list /public linklist(/constructor first null/no items on list yet /public boolean isempty(/true if list is empty return (first==null)/public void insertfirst(double dd/insert at start of list