A singleton null object Iterator implementation. : Iterator « Collections Data Structure « Java

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Java » Collections Data Structure » Iterator   A singleton null object Iterator implementation.          import java.util.Iterator; import java.util.NoSuchElementException; /*********************************************************************  * A singleton null object Iterator implementation.  *   * @version 2003-05-12  * @since 2003-05-10  * @author <a href="http://www.CroftSoft.com/">David Wallace Croft</a>  *********************************************************************/ public final class NullIterator implements Iterator // //////////////////////////////////////////////////////////////////// // //////////////////////////////////////////////////////////////////// {   public static final NullIterator INSTANCE = new NullIterator();   // ////////////////////////////////////////////////////////////////////   // ////////////////////////////////////////////////////////////////////   public boolean hasNext() {     return false;   }   public Object next() {     throw new NoSuchElementException();   }   public void remove() {     throw new UnsupportedOperationException();   }   // ////////////////////////////////////////////////////////////////////   // ////////////////////////////////////////////////////////////////////   private NullIterator() {   }   // ////////////////////////////////////////////////////////////////////   // //////////////////////////////////////////////////////////////////// }                                           Related examples in the same category 1. Listing the Elements of a Collection 2. De-mystify the Iterator interface, showing how to write a simple Iterator for an Array of Objects 3. Iterate over Set 4. Demonstrate iterators. 5. Use the for-each for loop to cycle through a collection. 6. List Iterator 7. Iterate a Collection and remove an item (Exception, wrong version) 8. Use an Iterator and remove the item with Iterator.remove() 9. An Iterator wrapper for an Enumeration. 10. EmptyIterator is an iterator which is empty. 11. Implements an java.util.Iterator over any array 12. Treat an Iterator as an Iterable 13. Iterator class for sparse values in an array. 14. Iterator class for values contained in an array range. 15. Array Iterator 16. Cyclic Iteration 17. Create singleton Iterator 18. Empty Iterator 19. An Iterator that wraps a number of Iterators 20. An Iterator to iterate over the elements of an array 21. Sorted Iterator 22. Iterator Union of Iterators 23. Iterator Utils 24. Linked Iterator 25. Prefetch Iterator 26. Protects an given iterator by preventing calls to remove(). 27. An Iterator that returns the elements of a specified array, or other iterators etc. 28. An Iterator wrapper for an Object[], allow us to deal with all array like structures in a consistent manner. 29. An array iterator 30. Adapt iterator to iterable 31. Static utility methods, classes, and abstract classes for iteration. 32. Iterator Collection 33. Convert Iterable to List