arrayiterator.java

一个普通的计算器程序

//********************************************************************
//  ArrayIterator.java       Authors: Lewis/Chase
//
//  Represents an iterator over the elements of an array.
//********************************************************************
package jss2;
import java.util.*;

public class ArrayIterator<T> implements Iterator
{
   private int count;    // the number of elements in the collection
   private int current;  // the current position in the iteration 
   private T[] items; 

   /******************************************************************
     Sets up this iterator using the specified items.
   ******************************************************************/
   public ArrayIterator (T[] collection, int size)
   {
      items = collection;
      count = size;
      current = 0;
   }

   /******************************************************************
     Returns true if this iterator has at least one more element
     to deliver in the iteraion.
   ******************************************************************/
   public boolean hasNext()
   {
      return (current < count);
   }

   /******************************************************************
     Returns the next element in the iteration. If there are no
     more elements in this itertion, a NoSuchElementException is
     thrown.
   ******************************************************************/
   public T next()
   {
      if (! hasNext())
         throw new NoSuchElementException();

 	 current++;
      return items[current - 1]; 
   }

   /******************************************************************
     The remove operation is not supported in this collection.
   ******************************************************************/
   public void remove() throws UnsupportedOperationException
   {
      throw new UnsupportedOperationException();
   }
}