Question

Create a program named NonZeroNumQueue.java then copy the contents from NonZeroNumQueue.txt. 
Then implement enqueue method. To get credit, DO NOT add or alter any data members/methods except 
the enqueue(int num). The NonZeroNumQueue will NOT accept zero, which mean you can enqueue any 
whole numbers EXCEPT 0(zero). You have already noticed that the queue is NEVER full, so the isFull() always returns false.

given

NonZeroNumQueue.txt

public class NonZeroNumQueue{
private int[] data;
private int total;
private int front;
private int tail;
public NonZeroNumQueue(){
data=new int[10];
total=0;
front=tail=0;
}
public void enqueue(int num){
//Implement this method here
}
public void dequeue(){
if(!isEmpty()){
total--;
front = (front+1) %data.length;
}
}
public int peek(){
if(isEmpty())
return 0; //0 means the queue is empty
return data[front];
}
public boolean isEmpty(){
return total==0;
}
public boolean isFull(){
return false;
}
public int size(){
return total;
}
}

Answer 1

// here is the full code
// output is attached
// plz comment if you need any clarification
// hit like if you liked it

// CODE
import java.io.*;

public class NonZeroNumQueue{
   private int[] data;
   private int total;
   private int front;
   private int tail;
  
    public NonZeroNumQueue(){
      data=new int[10];
      total=0;
      front=tail=0;
   }
   public void enqueue(int num) throws Exception{
       //Implement this method here
       if(num == 0) { // if number is zero throw exception
           throw new Exception("Exception : Trying to insert zero to the queue");
       } else{ // if it is not zero then add it to the queue
           if(!isFull()) { // if queue is not full
               data[tail] = num; // add number at the end of the queue
               tail = (tail+1) % data.length; // update tail pointer
               total++; // increment the number of elements in the queue
           }
       }
   }
   public void dequeue(){
      if(!isEmpty()){
         total--;
         front = (front+1) %data.length;
      }
   }
   public int peek(){
      if(isEmpty())
         return 0; //0 means the queue is empty
      return data[front];
   }
   public boolean isEmpty(){
      return total==0;
   }
   public boolean isFull(){
      return false;
   }
   public int size(){
      return total;
   }
}

// Driver class to test the above Queue
// You can remove this class, if you want to
// This class is added to test above Queue
public class Chegg218 {
    public static void main(String... args) {
        NonZeroNumQueue queue = new NonZeroNumQueue();
       
        // add elements
        try {
            queue.enqueue(2);
            System.out.println("2 is added");
            queue.enqueue(3);
            System.out.println("3 is added");
            queue.enqueue(1);
            System.out.println("1 is added");
            queue.enqueue(5);
            System.out.println("5 is added");
            queue.enqueue(0); // exception Occurred
            System.out.println("0 is added");
            queue.enqueue(23);
            System.out.println("23 is added");
        } catch(Exception e) { // if any exception is throwed, it will be catched here
            System.out.println(e); // print the error message
        }    
    }
}

// OUTPUT

Your Output (stdout) 2 is added 3 is added 1 is added 5 is added java.lang. Exception: Exception Trying to insert zero to the queue