Null Pointer Exception

[wrangler0987]

I have to write two new classes into a Queue class that implements through an array. It seems so simple and I'm almost completely positive that all the main componets are there. However, when trying to test it anything that I have altered in the classes SwitchEnds and in Equalize comes back with a java.lang.NullPointerException. I am at my breaking point as it seems I have used the same methods used in the Enqueue and Dequeue methods(which work flawlessly). I can't understand this at all and any help will be greatly appreciated.

The class-

public class Queue<QueueItem>
{
private Object[] Array;
private int Front, Rear, QueueMax;
private Object QueueItem;
 
public Queue(int Capacity)
{
Array = new Object[Capacity+1];
QueueMax = Capacity;
Front = 0;
Rear = 0;
return;
}
// end constructor
 
public Queue()
{
Array = new Object[1001];
QueueMax = 1000;
Front = 0;
Rear = 0;
return;
}
// end constructor
 
public void Enqueue(QueueItem QI)
{
Array[Rear] = QI;
 
if (Rear == QueueMax)
Rear = 0;
else
Rear++;
// end if
 
if (Front == Rear)
{
System.out.println("Queue Overflow");
System.exit(0);
}
// end if
return;
}
// end public method Enqueue
 
public QueueItem Dequeue()
{
QueueItem QI;
 
if (Front == Rear)
{
System.out.println("Queue Underflow!");
System.exit(0);
}
// end if
 
QI = (QueueItem) Array[Front];
if (Front == QueueMax)
Front = 0;
else
Front++;
// end if
 
return QI;
}
// end public method Dequeue
 
public void MakeEmpty()
{
Front = 0;
Rear = 0;
return;
}
// end public method MakeEmpty
 
public boolean IsEmpty()
{
if (Front == Rear)
return true;
else
return false;
// end if
}
// end public method IsEmpty
 
public boolean IsFull()
{
int F=Front, R=Rear+1;
 
if (R == QueueMax+1)
R = 0;
// end if
 
if (F == R)
return true;
else
return false;
// end if
}
// end public method IsFull
public void SwitchEnds()
{
if(this.LengthQueue() <= 1)
return;
 
Object QI, QI2;
QI = (QueueItem) Array[Rear];
QI2 = (QueueItem) Array[Front];
Array[Rear] = QI2;
Array[Front] = QI;
return;
}
 
public void Equalize(Queue<QueueItem> Q)
{
QueueItem Temp;
int Length1, Length2, NumberLeftInLongerQueue;
 
Length1 = this.LengthQueue();
Length2 = Q.LengthQueue();
 
if (Length1 < Length2)
{
Q.Equalize(this);
return;
}
 
if (Length1 - Length2 <= 1)
return;
 
NumberLeftInLongerQueue = (Length1 - Length2) / 2;
if((NumberLeftInLongerQueue + Q.LengthQueue()) > Q.QueueMax)
{
System.out.println("The smaller queue does not have a large enough capacity.");
System.exit(0);
}
 
for (int i = 1; i <= NumberLeftInLongerQueue; i++)
{
Temp = (QueueItem) Array[Rear];
if(Rear == 0 )
Rear = QueueMax;
else
Rear = Rear -1;
 
Q.Enqueue(Temp);
 
}
 
return;
 
}
public int LengthQueue()
{
if (Front <= Rear)
return Rear - Front;
else
return QueueMax - Front + Rear + 1;
// end while
}
// end public method LengthQueue
}
// end class Queue

[r035198x]

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