Object-Oriented Data-Structures - A Concise and Practical Introduction to Programming Algorithms in Java - page 188

Program 8.17 Minimal list implementation

class List
int element ;
List next ;

// Constructor
List( int el , List tail )

this .element=el;
this .next=tail;
}

List insertHead( int el)
return new List(el , this );
}

}

Let us now use this linked list data-structure for supporting the methods
provided by the stack:

Program 8.18 Implementing the stack interface using a linked list as its
backbone data-structure
class Stack
{ List

list ;

Stack ()
list= null ;
}

void Push( int el)
if (list!= null )
list=list . insertHead( el ) ;
else
list= new List(el , null );

}

int Pull ()
{ int val ;
if (list!= null )
{ val=list . element ;
list=list .next; }
else val= − 1;

return val ;
}
}