Frist last list
class Link { public long dData; public Link next; public Link(long d){ dData = d; } public void displayLink(){ System.out.print(dData + " "); } } public class FirstLastList1 { private Link first; private Link last; public FirstLastList1() { first = null; last = null; } public boolean isEmpty() { return first == null; } public void insertLast(long dd){ Link newLink = new Link(dd); if (isEmpty()) first = newLink; else last.next = newLink; last = newLink; } public long deleteFirst(){ long temp = first.dData; if (first.next == null) last = null; first = first.next; return temp; } public void displayList() { Link current = first; while (current != null){ current.displayLink(); current = current.next; } System.out.println(""); } } class LinkQueue { private FirstLastList1 theList; public LinkQueue() { theList = new FirstLastList1(); } public boolean isEmpty(){ return theList.isEmpty(); } public void insert(long j){ theList.insertLast(j); } public long remove() { return theList.deleteFirst(); } public void displayQueue() { System.out.print("Queue: "); theList.displayList(); } public static void main(String[] args) { LinkQueue theQueue = new LinkQueue(); theQueue.insert(20); theQueue.insert(40); theQueue.displayQueue(); theQueue.insert(60); theQueue.insert(80); theQueue.displayQueue(); theQueue.remove(); theQueue.remove(); theQueue.displayQueue(); } }