Queue类的toString（）方法

Question

Just a simple question, if I created a Queue class and initialized this

Queue queue = new Queue(5)

In the main method, and then enqueued and dequeued accordingly,

with the following instance variables, and toString() method:

 private int maxSize;
 private Planes[] queArray; 
 private int front;
 private int rear;
 private int nItems;

 public String toString()
 {
   String result = "[";
   for(int i = 0; i <= rear; i++)
   {
     result += " " + queArray[i];

     if(i <= rear - 1)
       result += ",";
   }
   result += " ]";
   return result;
 }//toString`

What variable do I stop at in the for loop:

for(int i = 0; i <= rear; i++) ,

Right now I have it at rear , which doesn't seem to work how I want it to, and I know it's not nItems , or maxSize because that will print the entire queue , including the empty slots, and I just want the updated queue . I know for a Stack , you only print up to the top variable, but I'm more confused for the Queue class.

These are my enqueue and dequeue methods:

 public void enqueue(Plane name)
 {
   if(rear == maxSize-1)
   {
     rear = -1;
   }
   rear++;
   queArray[rear] = name;
   nItems++;
 }

 public Plane dequeue()
 {
   Plane temp = queArray[front];
   front++;
   if(front == maxSize)
   {
     front = 0;
   }
   nItems--;
   return temp;
 }

Answer 1

When you do queue and deque you should manipulate a variable inside the class. So in the beginning it will be equal to 0. After each queue or dequeue accordingly you will ++ or -- it.

Then this is the variable you use in toString to define end boundary for the loop. To use it anywhere in the class like this it should be an instance variable too.

edit: After the code you added, seems like it should be nitems