Class TFloatLongIterator
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 (TFloatLongIterator it = map.iterator(); it.hasNext();) { it.advance(); if (satisfiesCondition(it.key()) { doSomethingWithValue(it.value()); } }
// modifying values in-place through iteration: for (TFloatLongIterator it = map.iterator(); it.hasNext();) { it.advance(); if (satisfiesCondition(it.key()) { it.setValue(newValueForKey(it.key())); } }
// deleting entries during iteration: for (TFloatLongIterator it = map.iterator(); it.hasNext();) { it.advance(); if (satisfiesCondition(it.key()) { it.remove(); } }
// faster iteration by avoiding hasNext(): TFloatLongIterator iterator = map.iterator(); for (int i = map.size(); i-- > 0;) { iterator.advance(); doSomethingWithKeyAndValue(iterator.key(), iterator.value()); }
- Version:
- $Id: P2PIterator.template,v 1.1 2006/11/10 23:28:00 robeden Exp $
- Author:
- Eric D. Friedman
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Field Summary
FieldsModifier and TypeFieldDescriptionprotected int
the number of elements this iterator believes are in the data structure it accesses.protected final TPrimitiveHash
the collection on which this iterator operates.protected int
the index used for iteration. -
Constructor Summary
ConstructorsConstructorDescriptionCreates an iterator over the specified map -
Method Summary
Modifier and TypeMethodDescriptionvoid
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.float
key()
Provides access to the key of the mapping at the iterator's position.protected final void
Sets the internal index so that the `next' object can be returned.protected final int
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.long
setValue
(long val) Replace the value of the mapping at the iterator's position with the specified value.long
value()
Provides access to the value of the mapping at the iterator's position.
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Field Details
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_hash
the collection on which this iterator operates. -
_expectedSize
protected int _expectedSizethe number of elements this iterator believes are in the data structure it accesses. -
_index
protected int _indexthe index used for iteration.
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Constructor Details
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TFloatLongIterator
Creates an iterator over the specified map
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Method Details
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advance
public void advance()Moves the iterator forward to the next entry in the underlying map.- Throws:
NoSuchElementException
- if the iterator is already exhausted
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key
public float key()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.- Returns:
- the key of the entry at the iterator's current position.
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value
public long value()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.- Returns:
- the value of the entry at the iterator's current position.
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setValue
public long setValue(long val) 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.- Parameters:
val
- the value to set in the current entry- Returns:
- the old value of the entry.
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nextIndex
protected final int nextIndex()Returns the index of the next value in the data structure or a negative value if the iterator is exhausted.- Returns:
- an
int
value - Throws:
ConcurrentModificationException
- if the underlying collection's size has been modified since the iterator was created.
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hasNext
public boolean hasNext()Returns true if the iterator can be advanced past its current location.- Returns:
- a
boolean
value
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remove
public void remove()Removes the last entry returned by the iterator. Invoking this method more than once for a single entry will leave the underlying data structure in a confused state. -
moveToNextIndex
protected final void moveToNextIndex()Sets the internal index so that the `next' object can be returned.
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