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java.lang.Object | +--gnu.trove.TIterator | +--gnu.trove.TPrimitiveIterator | +--gnu.trove.TLongIntIterator
Iterator for maps of type long and int.
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 (TLongIntIterator it = map.iterator(); it.hasNext();) { it.forward(); if (satisfiesCondition(it.key()) { doSomethingWithValue(it.value()); } }
// modifying values in-place through iteration: for (TLongIntIterator it = map.iterator(); it.hasNext();) { it.forward(); if (satisfiesCondition(it.key()) { it.setValue(newValueForKey(it.key())); } }
// deleting entries during iteration: for (TLongIntIterator it = map.iterator(); it.hasNext();) { it.forward(); if (satisfiesCondition(it.key()) { it.remove(); } }
// faster iteration by avoiding hasNext(): TLongIntIterator iterator = map.iterator(); for (int i = map.size(); i-- > 0;) { iterator.advance(); doSomethingWithKeyAndValue(iterator.key(), iterator.value()); }
Field Summary | |
protected int |
_expectedSize
the number of elements this iterator believes are in the data structure it accesses. |
protected TPrimitiveHash |
_hash
the collection on which this iterator operates. |
protected int |
_index
the index used for iteration. |
Constructor Summary | |
TLongIntIterator(TLongIntHashMap map)
Creates an iterator over the specified map |
Method Summary | |
void |
advance()
Moves the iterator forward to the next entry in the underlying map. |
boolean |
hasNext()
Returns true if the iterator can be advanced past its current location. |
long |
key()
Provides access to the key of the mapping at the iterator's position. |
protected void |
moveToNextIndex()
Sets the internal index so that the `next' object can be returned. |
protected int |
nextIndex()
Returns the index of the next value in the data structure or a negative value if the iterator is exhausted. |
void |
remove()
Removes the last entry returned by the iterator. |
int |
setValue(int val)
Replace the value of the mapping at the iterator's position with the specified value. |
int |
value()
Provides access to the value of the mapping at the iterator's position. |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
protected final TPrimitiveHash _hash
protected int _expectedSize
protected int _index
Constructor Detail |
public TLongIntIterator(TLongIntHashMap map)
Method Detail |
public void advance()
NoSuchElementException
- if the iterator is already exhaustedpublic long key()
public int value()
public int setValue(int val)
val
- the value to set in the current entry
protected final int nextIndex()
nextIndex
in class gnu.trove.TIterator
int
value
java.util.ConcurrentModificationException
- if the underlying collection's
size has been modified since the iterator was created.public boolean hasNext()
boolean
valuepublic void remove()
protected final void moveToNextIndex()
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