Structuring Data with Java - Java - page 275

Discussion

To make data from one part of your program available in a storage-independent way to other
parts of the code, generate an Iterator . Here is a short program that constructs, upon re-
quest, an Iterator for some data that it is storing—in this case, in an array. The Iterator
interface has only three methods— hasNext() , next() , and remove() :

package package com . darwinsys . util ;

import import java.util.Iterator java.util.Iterator ;

import import java.util.NoSuchElementException java.util.NoSuchElementException ;

/** Demonstrate the Iterator and Iterable interfaces, showing how
* to write a simple Iterator for an Array of Objects.
* @author Ian Darwin, http://www.darwinsys.com/
*/
public

public class implements Iterable < T >, Iterator < T > {

/** The data to be iterated over. */
protected

class ArrayIterator ArrayIterator < T > implements

protected T [] data ;

protected protected int int index = 0 ;

/** Construct an ArrayIterator object.
* @param d The array of objects to be iterated over.
*/
public public ArrayIterator ( final final T [] d ) {

setData ( d );

}

/** (Re)set the data array to the given array, and reset the iterator.
* @param d The array of objects to be iterated over.
*/
public

public void void setData ( final final T [] d ) {

this this . data = d ;

index = 0 ;

}

// -------------------
// Methods of Iterable
// -------------------

@Override
public public Iterator < T > iterator () {

index = 0 ;