Need HelP In JaVa

Hi hio,
Please check the following piece of code showing how to write enqueue(), dequeue(), isEmpty() and size() methods in your class. I just made a rough class, based on your mentioned cases- you have to modify enqueue() and dequeue() methods accordingly. One more thing what you want to do in front() method ? I am not clear so I have not implemented that one.

/*
 * ArrayQueue.java
 *
 * Created on June 10, 2009, 9:28 AM
 */

package myjava;

/**
 *
 * @author shalinig
 */
public class ArrayQueue{

    public Object Q[] = null;

    private int front,rear;
    private int size;

   /** Creates a new instance of ArrayQueue*/
    public ArrayQueue(int capacity) {
        Q = new Object[capacity];
        front = 0;
        rear = capacity; 
        size = 0;
          }
    
   public boolean enqueue(Object x) throws ArrayIndexOutOfBoundsException{
       
       if((front + 1 ==rear ) || ((front +1 == size) && rear ==0)){
           
           return false;//queue is full
       }
       else{
           Q[front++] = x;
           size++;
   }
       return true;
   }
      
   
    public Object dequeue() throws ArrayIndexOutOfBoundsException{
       
        if (rear == front) {
            // queue is empty
            return null; 
        } else  {
            // return object
            size--;
            Object obj = Q[rear];
            Q[rear] = null;
            rear++;
            return obj;
        }

   }
    
    public int getSize(){
       return this.getSize();
    }
    
    public boolean isEmpty(){
        return (size==0?true:false);
    }
}
  
  

Let me know if any issues. 😀

Thanks !

i really appreciate your help ,,

but what have you done is for the first one only,,

can you help me with the other ,,

thanks,,

hio

can you help me with the other ,,

thanks,,

Ha ha ! Too good man. 😀 Try to understand what I have done in my program(obviously something wrong would be there) and then you would understand yourself what changes you need to do in enqueue() and dequeue() methods accordingly for all cases.

ok ,, ok ,, I will ,,

if you don't mind see what i have dine until now :d

public class ArrayQueue2
{
private Object Q[];
private int front,rear;
private int size;

public ArrayQueue2(int capacity)
{
Q = new Object [capacity];
front = 0;
rear = -1;
}

public void enqueue (Object o)
{
if (front == ( rear + 2 ) % Q.length)
{
System.out.println("full quene");
}
else
{
rear = ( rear + 1 )% Q.length;
Q[rear] = o;
}
}

public Object dequene()
{
if (isEmpty())
{
System.out.println("empty quene");
return null;
}
else
{
Object o = Q[front];
front = ( front + 1 ) % Q.length;
return o;
}

}

public int size()
{
return ( Q.length + rear - front + 1 ) % Q.length;
}

public Object front()
{
if (this.isEmpty())
{
System.out.println("Empty queue");
return null;
}
else
{
return Q[front];
}
}

public boolean isEmpty()
{
return size() == 0;
}
}

is't wright :d

Superb hio,

but why you are using size variable? Where you are setting its value ? You can remove that I guess.

Why you are setting rear=-1 ?

Thanks,,

I didn't notice the rear in the first answer :d

Since you asked me about the rear why you set it as rear = capacity;?? ,,

and the size i will deal with it 😛

hio

Thanks,,

I didn't notice the rear in the first answer :d

Since you asked me about the rear why you set it as rear = capacity;?? ,,

and the size i will deal with it 😛

Man, if we see the literal meaning of rear, it means end and your setting it to -1 means you are putting it before front. Anyways it is going to affect much.

Go the way you want to go.😀

OK Bhot THANK you mera dost