Java Queue pro

Queue introduction & array based implementation

package com.java2novice.ds.queue;

public class QueueImpl

{    

    private int capacity;

    int queueArr[];

    int front = 0;

    int rear = -1;

    int currentSize = 0;

public QueueImpl(int queueSize)

{

        this.capacity = queueSize;

        queueArr = new int[this.capacity];

  }

           public void enqueue(int item)

           {

        if (isQueueFull())

        {

            System.out.println("Overflow ! Unable to add element: "+item);

        }

        else

           {

            rear++;

            if(rear == capacity-1)

           {

                rear = 0;

            }

            queueArr[rear] = item;

            currentSize++;

            System.out.println("Element " + item+ " is pushed to Queue !");

        }

    }

 public void dequeue()

{

        if (isQueueEmpty())

         {

            System.out.println("Underflow ! Unable to remove element from Queue");

        }

        else

            {

            front++;

            if(front == capacity-1)

            {

                System.out.println("Pop operation done ! removed: "+queueArr[front-1]);

                front = 0;

            }

            else

            {

                System.out.println("Pop operation done ! removed: "+queueArr[front-1]);

            }

            currentSize--;

        }

    }

public boolean isQueueFull()

{

        boolean status = false;

        if (currentSize == capacity)

        {

            status = true;

        }

        return status;

    }

    public boolean isQueueEmpty()

       {

        boolean status = false;

        if (currentSize == 0)

        {

            status = true;

        }

        return status;

    }

    public static void main(String a[])

    {

        QueueImpl queue = new QueueImpl(4);

        queue.enqueue(4);

        queue.dequeue();

        queue.enqueue(56);

        queue.enqueue(2);

        queue.enqueue(67);

        queue.dequeue();

        queue.dequeue();

        queue.enqueue(24);

        queue.dequeue();

        queue.enqueue(98);

        queue.enqueue(45);

        queue.enqueue(23);

        queue.enqueue(435);

    }

}

Dynamic Queue implementation using arrays

package com.java2novice.ds.queue;

public class DynamicQueueImpl

{

private int capacity = 2;

    int queueArr[];

    int front = 0;

    int rear = -1;

    int currentSize = 0;

  public DynamicQueueImpl()

  {

        queueArr = new int[this.capacity];

   }

   public void enqueue(int item)

    {

            if (isQueueFull())

           {

            System.out.println("Queue is full, increase capacity...");

            increaseCapacity();

            }

        rear++;

        if(rear >= queueArr.length && currentSize != queueArr.length){

            rear = 0;

        }

        queueArr[rear] = item;

        currentSize++;

        System.out.println("Adding: " + item);

    }

    public void dequeue()

       {

        if (isQueueEmpty())

          {

            System.out.println("Underflow ! Unable to remove element from Queue");

        }

         else

           {

            front++;

            if(front > queueArr.length-1)

            {

                System.out.println("removed: "+queueArr[front-1]);

                front = 0;

            }

              else

             {

                System.out.println("removed: "+queueArr[front-1]);

            }

            currentSize--;

        }

    }

    public boolean isQueueFull()

    {

        boolean status = false;

        if (currentSize == queueArr.length)

        {

            status = true;

        }

        return status;

    }

    public boolean isQueueEmpty()

      {

        boolean status = false;

        if (currentSize == 0)

        {

            status = true;

        }

        return status;

    }

   private void increaseCapacity()

    {

        int newCapacity = this.queueArr.length*2;

        int[] newArr = new int[newCapacity];

        int tmpFront = front;

        int index = -1;

        while(true)

         {

            newArr[++index] = this.queueArr[tmpFront];

            tmpFront++;

            if(tmpFront == this.queueArr.length)

            {

                tmpFront = 0;

            }

            if(currentSize == index+1)

            {

                break;

            }

        }

        this.queueArr = newArr;

        System.out.println("New array capacity: "+this.queueArr.length);

        this.front = 0;

        this.rear = index;

    }

    public static void main(String a[])

    {

        DynamicQueueImpl queue = new DynamicQueueImpl();

        queue.enqueue(4);

        queue.dequeue();

        queue.enqueue(56);

        queue.enqueue(2);

        queue.enqueue(67);

        queue.dequeue();

        queue.enqueue(24);

        queue.enqueue(98);

        queue.dequeue();

        queue.dequeue();

        queue.dequeue();

        queue.enqueue(435);

        queue.dequeue();

        queue.dequeue();

    }

}