Write a method for the Queue class in the queue.java program (Listing 4.4) that

Question

Write a method for the Queue class in the queue.java program (Listing 4.4) that
displays the contents of the queue. Note that this does not mean simply
displaying the contents of the underlying array. You should show the queue
contents from the first item inserted to the last, without indicating to the
viewer whether the sequence is broken by wrapping around the end of the
array. Be careful that one item and no items display properly, no matter where
front and rear are.

Below is the program that needs to be modified in order to achieve the question's objective:

// queue.java
// demonstrates queue
// to run this program: C>java QueueApp
////////////////////////////////////////////////////////////////
class Queue
{
private int maxSize;
private long[] queArray;
private int front;
private int rear;
private int nItems;
//--------------------------------------------------------------
public Queue(int s) // constructor
{
maxSize = s;
queArray = new long[maxSize];
front = 0;
rear = -1;
nItems = 0;
}
//--------------------------------------------------------------
public void insert(long j) // put item at rear of queue
{
if(rear == maxSize-1) // deal with wraparound
rear = -1;
queArray[++rear] = j; // increment rear and insert
nItems++; // one more item
}
//--------------------------------------------------------------
public long remove() // take item from front of queue
{
long temp = queArray[front++]; // get value and incr front
if(front == maxSize) // deal with wraparound
front = 0;
nItems--; // one less item
return temp;
}
//--------------------------------------------------------------
public long peekFront() // peek at front of queue
{

return queArray[front];
}
//--------------------------------------------------------------
public boolean isEmpty() // true if queue is empty
{
return (nItems==0);
}
//--------------------------------------------------------------
public boolean isFull() // true if queue is full
{
return (nItems==maxSize);
}
//--------------------------------------------------------------
public int size() // number of items in queue
{
return nItems;
}
//--------------------------------------------------------------
} // end class Queue
////////////////////////////////////////////////////////////////
class QueueApp
{
public static void main(String[] args)
{
Queue theQueue = new Queue(5); // queue holds 5 items
theQueue.insert(10); // insert 4 items
theQueue.insert(20);
theQueue.insert(30);
theQueue.insert(40);
theQueue.remove(); // remove 3 items
theQueue.remove(); // (10, 20, 30)
theQueue.remove();
theQueue.insert(50); // insert 4 more items
theQueue.insert(60); // (wraps around)
theQueue.insert(70);
theQueue.insert(80);
while( !theQueue.isEmpty() ) // remove and display
{ // all items

long n = theQueue.remove(); // (40, 50, 60, 70, 80)
System.out.print(n);
System.out.print(

Explanation / Answer

public class Queue { private int maxSize; private int[] queArray; private int front; private int rear; private int nItems; public Queue(int s) { maxSize = s; queArray = new int[maxSize]; front = 0; rear = -1; nItems = 0; } public void insert(int j) { if (rear == maxSize - 1) rear = -1; queArray[++rear] = j; nItems++; } public int remove() { int removed = queArray[front++]; if (front == maxSize) front = 0; nItems--; return removed; } public int peek() { return queArray[front]; } public boolean isEmpty() { return (nItems == 0); } public boolean isFull() { return (nItems == maxSize); } public int size() { return nItems; } public void display() { System.out.println("First Inserted Item to Last Inserted Item"); if (rear

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