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. The index of the
current character can be retrieved by calling getIndex. Calling setIndex
will move the iterator to a new position within the sequence of characters.
If at any time the iterator's current index moves outside the range of
getBeginIndex and getEndIndex, previous() and next() will return DONE, signaling that
the iterator has reached the end of the sequence.
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.prev()) {
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.prev()) {}
int start = iter.getIndex();
processSection(start,end);
}
Set the position to the specified position in the text and return that
character.
DONE
public static final char DONE
Constant that is returned when the iterator has reached either the end
or the beginning of the text. The unicode 2.0 standard states that
'\\uFFFF' is an invalid unicode value and should not occur in any valid
unicode string.
Increment the iterator's index by one and return the character
at the new index. If the resulting index is greater or equal
to getEndIndex(), the current index is reset to getEndIndex() and
a value of DONE is returned.
Returns:
the character at the new position or DONE if the current
position is off the end of the text.
Decrement the iterator's index by one and return the character
at the new index. If the resulting index is
less than getBeginIndex(), the current index is reset to getBeginIndex()
and a value of DONE is returned.
Returns:
the character at the new position or DONE if the current
position is off the end of the text.
setIndex
public abstract char setIndex(int position)
Set the position to the specified position in the text and return that
character.
Parameters:
position - the position within the text. Valid values range from
getBeginIndex() to getEndIndex() - 1. An IllegalArgumentException is thrown
if an invalid value is supplied.
DONE
clone()
DONE
first