Collections, Maps and Iterators - Absolute Java - page 930

Display 16.14 For-Each Loops as Iterators (part 2 of 2)

18 s.remove(last);

19 System.out.println();
20 System.out.println("The set now contains:");

21 for (String e : s)
22 System.out.println(e);

23 System.out.println("End of program.");
24 }
25 }

The output is the same as in Display 16.13.

List Iterators
The collection framework has two iterator interfaces: the Iterator<T> interface, which
you have already seen and which works with any collection class that implements the
Collection<T> interface; and the ListIterator<T> interface, which is designed to
work with collections that implement the List<T> interface. The ListIterator<T>
interface extends the Iterator<T> interface. A ListIterator<T> has all the methods
that an Iterator<T> has, plus more methods that provide two new abilities: A
ListIterator<T> can move in either direction along the list of elements in the
collection, and a ListIterator<T> has methods, such as set and add , that can be
used to change the elements in the collection. The methods for the ListIterator<T>
interface are given in Display 16.15 . See Appendix 5 for a more detailed description
that includes all exceptions thrown.
The map framework does not directly support the iterable interface, but you can use
the map's keySet() , values() , or entrySet() methods, which return iterable sets
containing the keys, values, or (key, value) mappings of the map.

List
Iterator<T>

Display 16.15 Methods in the ListIterator<T> Interface (part 1 of 2)

The ListIterator<T> interface is in the java.util package.
The cursor position is explained in the text and in Display 16.16.
All the exception classes mentioned are the kind that are not required to be caught in a catch
block or declared in a throws clause.
NoSuchElementException is in the java.util package, which requires an import statement
if your code mentions the NoSuchElementException class. All the other exception classes
mentioned are in the package java.lang and so do not require any import statement.

public T next()
Returns the next element of the list that produced the iterator. More specifically, returns the
element immediately after the cursor position.
Throws a NoSuchElementException if there is no next element.