gnu.trove
Class TObjectLongIterator

java.lang.Object
  extended by gnu.trove.TIterator
      extended by gnu.trove.TObjectLongIterator

public class TObjectLongIterator
extends TIterator

Iterator for maps of type Object and long.

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 (TObjectLongIterator it = map.iterator();
      it.hasNext();) {
   it.forward();
   if (satisfiesCondition(it.key()) {
     doSomethingWithValue(it.value());
   }
 }
 
 // modifying values in-place through iteration:
 for (TObjectLongIterator it = map.iterator();
      it.hasNext();) {
   it.forward();
   if (satisfiesCondition(it.key()) {
     it.setValue(newValueForKey(it.key()));
   }
 }
 
 // deleting entries during iteration:
 for (TObjectLongIterator it = map.iterator();
      it.hasNext();) {
   it.forward();
   if (satisfiesCondition(it.key()) {
     it.remove();
   }
 }
 
 // faster iteration by avoiding hasNext():
 TObjectLongIterator iterator = map.iterator();
 for (int i = map.size(); i-- > 0;) {
   iterator.advance();
   doSomethingWithKeyAndValue(iterator.key(), iterator.value());
 }
 

Version:
$Id: TObjectLongIterator.java,v 1.1 2002/09/22 21:53:42 ericdf Exp $
Author:
Eric D. Friedman

Field Summary
private  TObjectLongHashMap _map
           
 
Fields inherited from class gnu.trove.TIterator
_expectedSize, _hash, _index
 
Constructor Summary
TObjectLongIterator(TObjectLongHashMap map)
           
 
Method Summary
 void advance()
          Moves the iterator forward to the next entry in the underlying map.
 java.lang.Object key()
          Provides access to the key of the mapping at the iterator's position.
protected  int nextIndex()
          Returns the index of the next value in the data structure or a negative value if the iterator is exhausted.
 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.
 
Methods inherited from class gnu.trove.TIterator
hasNext, moveToNextIndex, remove
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

_map

private final TObjectLongHashMap _map
Constructor Detail

TObjectLongIterator

public TObjectLongIterator(TObjectLongHashMap map)
Method Detail

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.

Specified by:
nextIndex in class TIterator
Returns:
an int value

advance

public void advance()
Moves the iterator forward to the next entry in the underlying map.

Throws:
NoSuchElementException - if the iterator is already exhausted

key

public java.lang.Object 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.

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.

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.