public class AnnotationComboIterator extends Object implements Iterable<AnnotationIteratorPair>, Iterator<AnnotationIteratorPair>
This class supports a common idiom in UIMA annotation iteration, where you need to iterate over two kinds of annotations in lock-step. For example, you often want to iterate over all sentences, then do something on each sentence and all tokens in that sentence. Here's how to do this with this class.
CAS cas = ... Type sentenceType = ..., tokenType = ... // Init with CAS, upper and lower type. AnnotationComboIterator it = new AnnotationComboIterator(cas, sentenceType, tokenType); // Iterate over sentences for (AnnotationIteratorPair aiPair : it) { // Obtain sentence annotation AnnotationFS sentence = aiPair.getAnnotation(); // Do something with sentence... // Iterate over tokens for (AnnotationFS token : aiPair.getSubIterator()) { // Do something with tokens... } }The combo iterator returns in its
next()
method a pair of an annotation of the upper
type (e.g., sentence), and an iterator over annotations of the lower type (e.g., tokens). Note
that both the upper and lower iterator also implement the Iterable interface and can be use
directly in for-loops.
Note that only this usage is safe. To keep the implementation efficient, the combo iterator keeps two iterators internally that it increments in lock-step. Do not attempt, for example, to collect more than one of the subiterators (token iterator in our example). Do not use this class if your intended usage does not fall into this pattern.
Constructor and Description |
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AnnotationComboIterator(org.apache.uima.cas.CAS cas,
org.apache.uima.cas.Type upper,
org.apache.uima.cas.Type lower)
Create a new combo iterator.
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Modifier and Type | Method and Description |
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boolean |
hasNext() |
Iterator<AnnotationIteratorPair> |
iterator() |
AnnotationIteratorPair |
next() |
void |
remove()
Not supported.
|
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
forEach, spliterator
forEachRemaining
public AnnotationComboIterator(org.apache.uima.cas.CAS cas, org.apache.uima.cas.Type upper, org.apache.uima.cas.Type lower)
cas
- The CAS we're operating on.upper
- The type of the upper iterator, e.g., sentence.lower
- The type of the lower iterator, e.g., token.public boolean hasNext()
hasNext
in interface Iterator<AnnotationIteratorPair>
public AnnotationIteratorPair next()
next
in interface Iterator<AnnotationIteratorPair>
public Iterator<AnnotationIteratorPair> iterator()
iterator
in interface Iterable<AnnotationIteratorPair>
public void remove()
remove
in interface Iterator<AnnotationIteratorPair>
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