Lists, Stacks, and Queues - Data Structures and Algorithm Analysis - page 130

/ ** Linkedqueueimplementation * /
classLQueue<E>implementsQueue<E>{
privateLink<E>front; //Pointertofrontqueuenode
privateLink<E>rear; //Pointertorearqueuenode
intsize; //Numberofelementsinqueue

/ ** Constructors * /
publicLQueue(){init();}
publicLQueue(intsize){init();}//Ignoresize

/ ** Initializequeue * /
privatevoidinit(){
front=rear=newLink<E>(null);
size=0;

}

/ ** Reinitializequeue * /
publicvoidclear(){init();}

/ ** Putelementonrear * /
publicvoidenqueue(Eit){
rear.setNext(newLink<E>(it,null));
rear=rear.next();
size++;

}

/ ** Removeandreturnelementfromfront * /
publicEdequeue(){
assertsize!=0:"Queueisempty";
Eit=front.next().element();//Storedequeuedvalue
front.setNext(front.next().next());//Advancefront
if(front.next()==null)rear=front;//LastObject
size--;
returnit;

//ReturnObject

}

/ ** @returnFrontelement * /
publicEfrontValue(){
assertsize!=0:"Queueisempty";
returnfront.next().element();

}

/ ** @returnQueuesize * /
publicintlength(){returnsize;}

Figure4.28 Linked queue class implementation.