The iterator semantics for Trove's primitive maps is slightly different * from those defined in java.util.Iterator, but still well within * the scope of the pattern, as defined by Gamma, et al.
* *This iterator does not implicitly advance to the next entry when * the value at the current position is retrieved. Rather, you must explicitly * ask the iterator to advance() and then retrieve either the key(), * the value() or both. This is done so that you have the option, but not * the obligation, to retrieve keys and/or values as your application requires, and * without introducing wrapper objects that would carry both. As the iteration is * stateful, access to the key/value parts of the current map entry happens in * constant time.
* *In practice, the iterator is akin to a "search finger" that you move from * position to position. Read or write operations affect the current entry only and * do not assume responsibility for moving the finger.
* *Here are some sample scenarios for this class of iterator:
* *
* // accessing keys/values through an iterator:
* for (TDoubleLongIterator it = map.iterator();
* it.hasNext();) {
* it.forward();
* if (satisfiesCondition(it.key()) {
* doSomethingWithValue(it.value());
* }
* }
*
*
*
* // modifying values in-place through iteration:
* for (TDoubleLongIterator it = map.iterator();
* it.hasNext();) {
* it.forward();
* if (satisfiesCondition(it.key()) {
* it.setValue(newValueForKey(it.key()));
* }
* }
*
*
*
* // deleting entries during iteration:
* for (TDoubleLongIterator it = map.iterator();
* it.hasNext();) {
* it.forward();
* if (satisfiesCondition(it.key()) {
* it.remove();
* }
* }
*
*
*
* // faster iteration by avoiding hasNext():
* TDoubleLongIterator iterator = map.iterator();
* for (int i = map.size(); i-- > 0;) {
* iterator.advance();
* doSomethingWithKeyAndValue(iterator.key(), iterator.value());
* }
*
*
* @author Eric D. Friedman
* @version $Id: TDoubleLongIterator.java,v 1.1 2002/09/22 21:53:40 ericdf Exp $
*/
public class TDoubleLongIterator extends TPrimitiveIterator {
/** the collection being iterated over */
private final TDoubleLongHashMap _map;
/**
* Creates an iterator over the specified map
*/
public TDoubleLongIterator(TDoubleLongHashMap map) {
super(map);
this._map = map;
}
/**
* Moves the iterator forward to the next entry in the underlying map.
*
* @exception NoSuchElementException if the iterator is already exhausted
*/
public void advance() {
moveToNextIndex();
}
/**
* Provides access to the key of the mapping at the iterator's position.
* Note that you must advance() the iterator at least once
* before invoking this method.
*
* @return the key of the entry at the iterator's current position.
*/
public double key() {
return _map._set[_index];
}
/**
* Provides access to the value of the mapping at the iterator's position.
* Note that you must advance() the iterator at least once
* before invoking this method.
*
* @return the value of the entry at the iterator's current position.
*/
public long value() {
return _map._values[_index];
}
/**
* Replace the value of the mapping at the iterator's position with the
* specified value. Note that you must advance() the iterator at
* least once before invoking this method.
*
* @param val the value to set in the current entry
* @return the old value of the entry.
*/
public long setValue(long val) {
long old = value();
_map._values[_index] = val;
return old;
}
}// TDoubleLongIterator