public class TDoubleDoubleIterator extends TPrimitiveIterator
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 (TDoubleDoubleIterator it = map.iterator();
it.hasNext();) {
it.forward();
if (satisfiesCondition(it.key()) {
doSomethingWithValue(it.value());
}
}
// modifying values in-place through iteration:
for (TDoubleDoubleIterator it = map.iterator();
it.hasNext();) {
it.forward();
if (satisfiesCondition(it.key()) {
it.setValue(newValueForKey(it.key()));
}
}
// deleting entries during iteration:
for (TDoubleDoubleIterator it = map.iterator();
it.hasNext();) {
it.forward();
if (satisfiesCondition(it.key()) {
it.remove();
}
}
// faster iteration by avoiding hasNext():
TDoubleDoubleIterator iterator = map.iterator();
for (int i = map.size(); i-- > 0;) {
iterator.advance();
doSomethingWithKeyAndValue(iterator.key(), iterator.value());
}
| Modifier and Type | Field and Description |
|---|---|
private TDoubleDoubleHashMap |
_map
the collection being iterated over
|
_hash_expectedSize, _index| Constructor and Description |
|---|
TDoubleDoubleIterator(TDoubleDoubleHashMap map)
Creates an iterator over the specified map
|
| Modifier and Type | Method and Description |
|---|---|
void |
advance()
Moves the iterator forward to the next entry in the underlying map.
|
double |
key()
Provides access to the key of the mapping at the iterator's position.
|
double |
setValue(double val)
Replace the value of the mapping at the iterator's position with the
specified value.
|
double |
value()
Provides access to the value of the mapping at the iterator's position.
|
nextIndexhasNext, moveToNextIndex, removeprivate final TDoubleDoubleHashMap _map
public TDoubleDoubleIterator(TDoubleDoubleHashMap map)
public void advance()
NoSuchElementException - if the iterator is already exhaustedpublic double key()
public double value()
public double setValue(double val)
val - the value to set in the current entry