This interface defines a protocol for bidirectional iteration over text.
The iterator iterates over a bounded sequence of characters. Characters
are indexed with values beginning with the value returned by getBeginIndex() and
continuing through the value returned by getEndIndex()-1.
Iterators maintain a current character index, whose valid range is from
getBeginIndex() to getEndIndex(); the value getEndIndex() is included to allow
handling of zero-length text ranges and for historical reasons.
The current index can be retrieved by calling getIndex() and set directly
by calling setIndex(), first(), and last().
The methods previous() and next() are used for iteration. They return DONE if
they would move outside the range from getBeginIndex() to getEndIndex() -1,
signaling that the iterator has reached the end of the sequence. DONE is
also returned by other methods to indicate that the current index is
outside this range.
Examples:
Traverse the text from start to finish
public void traverseForward(CharacterIterator iter) {
for(char c = iter.first(); c != CharacterIterator.DONE; c = iter.next()) {
processChar(c);
}
}
Traverse the text backwards, from end to start
public void traverseBackward(CharacterIterator iter) {
for(char c = iter.last(); c != CharacterIterator.DONE; c = iter.previous()) {
processChar(c);
}
}
Traverse both forward and backward from a given position in the text.
Calls to notBoundary() in this example represents some
additional stopping criteria.
public void traverseOut(CharacterIterator iter, int pos) {
for (char c = iter.setIndex(pos);
c != CharacterIterator.DONE && notBoundary(c);
c = iter.next()) {
}
int end = iter.getIndex();
for (char c = iter.setIndex(pos);
c != CharacterIterator.DONE && notBoundary(c);
c = iter.previous()) {
}
int start = iter.getIndex();
processSection(start, end);
}
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