Class TShortObjectIterator<V>
- java.lang.Object
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- gnu.trove.TShortObjectIterator<V>
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public class TShortObjectIterator<V> extends java.lang.Object
Iterator for maps of type short and Object.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 (TShortObjectIterator it = map.iterator(); it.hasNext();) { it.advance(); if (satisfiesCondition(it.key()) { doSomethingWithValue(it.value()); } }
// modifying values in-place through iteration: for (TShortObjectIterator it = map.iterator(); it.hasNext();) { it.advance(); if (satisfiesCondition(it.key()) { it.setValue(newValueForKey(it.key())); } }
// deleting entries during iteration: for (TShortObjectIterator it = map.iterator(); it.hasNext();) { it.advance(); if (satisfiesCondition(it.key()) { it.remove(); } }
// faster iteration by avoiding hasNext(): TShortObjectIterator iterator = map.iterator(); for (int i = map.size(); i-- > 0;) { iterator.advance(); doSomethingWithKeyAndValue(iterator.key(), iterator.value()); }
- Version:
- $Id: P2OIterator.template,v 1.1 2006/11/10 23:28:00 robeden Exp $
- Author:
- Eric D. Friedman
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Field Summary
Fields Modifier and Type Field Description 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.
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Constructor Summary
Constructors Constructor Description TShortObjectIterator(TShortObjectHashMap<V> map)
Creates an iterator over the specified map
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description 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.short
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.V
setValue(V val)
Replace the value of the mapping at the iterator's position with the specified value.V
value()
Provides access to the value of the mapping at the iterator's position.
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Field Detail
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_hash
protected final TPrimitiveHash _hash
the collection on which this iterator operates.
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_expectedSize
protected int _expectedSize
the number of elements this iterator believes are in the data structure it accesses.
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_index
protected int _index
the index used for iteration.
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Constructor Detail
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TShortObjectIterator
public TShortObjectIterator(TShortObjectHashMap<V> map)
Creates an iterator over the specified map
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Method Detail
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advance
public void advance()
Moves the iterator forward to the next entry in the underlying map.- Throws:
java.util.NoSuchElementException
- if the iterator is already exhausted
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key
public short 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 V 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 V setValue(V 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:
java.util.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.
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moveToNextIndex
protected final void moveToNextIndex()
Sets the internal index so that the `next' object can be returned.
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