An iterator returns values from a collection. A collection can have many iterators, and each iterator is independent of all the others. In the next example, a list of integers is printed twice, by two iterators. The result is:

10 10
12 12
14 14
16 16
18 18
20 20

XML:
<dm:ints range="[0,20]2">
  <dm:iterator id="iter1"/>
  <dm:iterator id="iter2"/>
</dm:ints>

Java:
DatamixerIterator iter0 = // get iterator from XML context
DatamixerIterator iter1 = // get iterator from XML context
while (iter0.hasNext ())
    System.out.println (iter0.getNextValue () + " " + iter1.getNextValue ());

Iterators can also refer to a collection by its id:

<dm:ints id="even-ints" range="[0,20]2"/>
<dm:iterator id="iter1" collection="even-ints"/>
<dm:iterator id="iter2" collection="even-ints"/>

The Java implementation of a datamixer iterator is DatamixerIterator, which implements java.util.Iterator. Each call to next() calls getNextValue(), which gets the next value as a Value object.

The iterator stores this value as its current value. The current value can be accessed any number of times with getCurrentValue(), or as a Java Object with getCurrent().

next() returns this value as a Java Object, by calling value.getObject(). If the value is desired as a Value, then getNextValue() can be called directly instead of next().

A datamixer iterator supports several methods in addition to hasNext() and next():

• reset() resets the iterator to an initial state. The first call to next() after reset() will return the first element in the collection.
• getRepeat() and setRepeat() set the value of the repeat flag. If true, then when an iterator reaches the end of the collection, it is automatically reset.
• getCollection() and setCollection() return the collection that produced the iterator.
• getFormatPattern() and setFormatPattern() allow a format pattern to be applied to each next value.
• getId() and setId() associate an identifier with an iterator, which is used when printing error messages.