IteratorUtils

An iterator over no elements.

WARNING: This constant is binary incompatible with Commons Collections 2.1 and 2.1.1. Use EmptyIterator.INSTANCE for compatability with Commons Collections 2.1.1.

A list iterator over no elements.

WARNING: This constant is binary incompatible with Commons Collections 2.1 and 2.1.1. Use EmptyListIterator.INSTANCE for compatability with Commons Collections 2.1.1.

A map iterator over no elements.

An ordered iterator over no elements.

An ordered map iterator over no elements.

IteratorUtils is not normally instantiated.

Gets an iterator over part of an object or primitive array.

This method will handle primitive arrays as well as object arrays. The primitives will be wrapped in the appropriate wrapper class.

Gets an iterator over the end part of an object array.

WARNING: This method is binary incompatible with Commons Collections 2.1 and 2.1.1. Use new ArrayIterator(array,start) for compatability.

Gets an iterator over part of an object array.

WARNING: This method is binary incompatible with Commons Collections 2.1 and 2.1.1. Use new ArrayIterator(array,start,end) for compatability.

Gets an iterator over an object or primitive array.

This method will handle primitive arrays as well as object arrays. The primitives will be wrapped in the appropriate wrapper class.

Gets an iterator over an object array.

WARNING: This method is binary incompatible with Commons Collections 2.1 and 2.1.1. Use new ArrayIterator(array) for compatability.

Gets an iterator over the end part of an object or primitive array.

This method will handle primitive arrays as well as object arrays. The primitives will be wrapped in the appropriate wrapper class.

Gets a list iterator over part of an object or primitive array.

This method will handle primitive arrays as well as object arrays. The primitives will be wrapped in the appropriate wrapper class.

Gets a list iterator over an object array.

Gets a list iterator over part of an object array.

Gets a list iterator over the end part of an object or primitive array.

This method will handle primitive arrays as well as object arrays. The primitives will be wrapped in the appropriate wrapper class.

Gets a list iterator over an object or primitive array.

This method will handle primitive arrays as well as object arrays. The primitives will be wrapped in the appropriate wrapper class.

Gets a list iterator over the end part of an object array.

Gets an enumeration that wraps an iterator.

Gets an iterator that provides an iterator view of the given enumeration.

Gets an iterator that provides an iterator view of the given enumeration that will remove elements from the specified collection.

Gets an iterator that iterates through an array of Iterators one after another.

Gets an iterator that iterates through a collections of Iterators one after another.

Gets an iterator that iterates through two Iterators one after another.

Gets an iterator that provides an ordered iteration over the elements contained in a collection of ordered Iterators.

Given two ordered Iterators A and B, the next() method will return the lesser of A.next() and B.next().

The comparator is optional. If null is specified then natural order is used.

Gets an iterator that provides an ordered iteration over the elements contained in an array of Iterators.

Given two ordered Iterators A and B, the next() method will return the lesser of A.next() and B.next() and so on.

The comparator is optional. If null is specified then natural order is used.

Gets an iterator that provides an ordered iteration over the elements contained in a collection of Iterators.

Given two ordered Iterators A and B, the next() method will return the lesser of A.next() and B.next() and so on.

The comparator is optional. If null is specified then natural order is used.

Gets an empty iterator.

This iterator is a valid iterator object that will iterate over nothing.

WARNING: This method is binary incompatible with Commons Collections 2.1 and 2.1.1. Use EmptyIterator.INSTANCE for compatability with Commons Collections 2.1.1.

Gets an empty list iterator.

This iterator is a valid list iterator object that will iterate over nothing.

WARNING: This method is binary incompatible with Commons Collections 2.1 and 2.1.1. Use EmptyListIterator.INSTANCE for compatability with Commons Collections 2.1.1.

Gets an empty map iterator.

This iterator is a valid map iterator object that will iterate over nothing.

Gets an empty ordered iterator.

This iterator is a valid iterator object that will iterate over nothing.

Gets an empty ordered map iterator.

This iterator is a valid map iterator object that will iterate over nothing.

Gets an iterator that filters another iterator.

The returned iterator will only return objects that match the specified filtering predicate.

Gets a list iterator that filters another list iterator.

The returned iterator will only return objects that match the specified filtering predicate.

Gets a suitable Iterator for the given object.

This method can handles objects as follows

• null - empty iterator
• Iterator - returned directly
• Enumeration - wrapped
• Collection - iterator from collection returned
• Map - values iterator returned
• Dictionary - values (elements) enumeration returned as iterator
• array - iterator over array returned
• object with iterator() public method accessed by reflection
• object - singleton iterator

Gets an iterator that loops continuously over the supplied collection.

The iterator will only stop looping if the remove method is called enough times to empty the collection, or if the collection is empty to start with.

Gets an iterator that loops continuously over the supplied list.

The iterator will only stop looping if the remove method is called enough times to empty the list, or if the list is empty to start with.

Gets an iterator that operates over an object graph.

This iterator can extract multiple objects from a complex tree-like object graph. The iteration starts from a single root object. It uses a Transformer to extract the iterators and elements. Its main benefit is that no intermediate List is created.

For example, consider an object graph:

                 |- Branch -- Leaf
                 |         \- Leaf
         |- Tree |         /- Leaf
         |       |- Branch -- Leaf
  Forest |                 \- Leaf
         |       |- Branch -- Leaf
         |       |         \- Leaf
         |- Tree |         /- Leaf
                 |- Branch -- Leaf
                 |- Branch -- Leaf

 public Object transform(Object input) {
   if (input instanceof Forest) {
     return ((Forest) input).treeIterator();
   }
   if (input instanceof Tree) {
     return ((Tree) input).branchIterator();
   }
   if (input instanceof Branch) {
     return ((Branch) input).leafIterator();
   }
   if (input instanceof Leaf) {
     return input;
   }
   throw new ClassCastException();
 }

Internally, iteration starts from the root object. When next is called, the transformer is called to examine the object. The transformer will return either an iterator or an object. If the object is an Iterator, the next element from that iterator is obtained and the process repeats. If the element is an object it is returned.

Under many circumstances, linking Iterators together in this manner is more efficient (and convenient) than using nested for loops to extract a list.

Gets a singleton iterator.

This iterator is a valid iterator object that will iterate over the specified object.

WARNING: This method is binary incompatible with Commons Collections 2.1 and 2.1.1. Use new SingletonIterator(object) for compatability.

Gets a singleton list iterator.

This iterator is a valid list iterator object that will iterate over the specified object.

Gets an array based on an iterator.

As the wrapped Iterator is traversed, an ArrayList of its values is created. At the end, this is converted to an array.

Gets an array based on an iterator.

As the wrapped Iterator is traversed, an ArrayList of its values is created. At the end, this is converted to an array.

Gets a list based on an iterator.

As the wrapped Iterator is traversed, an ArrayList of its values is created. At the end, the list is returned.

Gets a list based on an iterator.

As the wrapped Iterator is traversed, an ArrayList of its values is created. At the end, the list is returned.

Gets a list iterator based on a simple iterator.

As the wrapped Iterator is traversed, a LinkedList of its values is cached, permitting all required operations of ListIterator.

Gets an iterator that transforms the elements of another iterator.

The transformation occurs during the next() method and the underlying iterator is unaffected by the transformation.

Gets an immutable version of an Iterator. The returned object will always throw an UnsupportedOperationException for the remove() method.

Gets an immutable version of a ListIterator. The returned object will always throw an UnsupportedOperationException for the remove(), add(E) and set(E) methods.

Gets an immutable version of a MapIterator. The returned object will always throw an UnsupportedOperationException for the remove(), setValue(Object) methods.