Iterable Simplified The following code shows how to implement custom Iterable object.
If the object implements Iterable interface it can be used as a target in
for each loop. The below example shows both forward and backward iteration.
package com.bethecoder.tutorials.collections; import java.util.Iterator; import java.util.NoSuchElementException; public class IterableTest { public static void main ( String [] args ) { String [] strings = { "ONE" , "TWO" , "THREE" , "FOUR" , "FIVE" , "SIX" } ; IterableObject iterableObj = new IterableObject ( strings ) ; ReverseIterableObject reverseIterableObj = new ReverseIterableObject ( strings ) ; for ( String str : iterableObj ) { System.out.println ( str ) ; } System.out.println ( "----------------" ) ; for ( String str : reverseIterableObj ) { System.out.println ( str ) ; } } } class IterableObject implements Iterable<String> { private String [] myStrings = null ; public IterableObject ( String [] myStrings ) { this .myStrings = myStrings; } public Iterator<String> iterator () { return new Iterator<String> () { private int count = 0 ; public boolean hasNext () { return count < myStrings.length; } public String next () { if ( count < myStrings.length ) { return myStrings [ count++ ] ; } throw new NoSuchElementException () ; } public void remove () { throw new UnsupportedOperationException () ; } } ; } } class ReverseIterableObject implements Iterable<String> { private String [] myStrings = null ; public ReverseIterableObject ( String [] myStrings ) { this .myStrings = myStrings; } public Iterator<String> iterator () { return new Iterator<String> () { private int count = myStrings.length- 1 ; public boolean hasNext () { return count >= 0 ; } public String next () { if ( count >= 0 ) { return myStrings [ count-- ] ; } throw new NoSuchElementException () ; } public void remove () { throw new UnsupportedOperationException () ; } } ; } }
ONE
TWO
THREE
FOUR
FIVE
SIX
----------------
SIX
FIVE
FOUR
THREE
TWO
ONE
