Package gnu.trove

Class TByteLongIterator

java.lang.Object
gnu.trove.TByteLongIterator

public class TByteLongIterator extends Object
Iterator for maps of type byte 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 (TByteLongIterator it = map.iterator();
      it.hasNext();) {
   it.advance();
   if (satisfiesCondition(it.key()) {
     doSomethingWithValue(it.value());
   }
 }
 
 // modifying values in-place through iteration:
 for (TByteLongIterator it = map.iterator();
      it.hasNext();) {
   it.advance();
   if (satisfiesCondition(it.key()) {
     it.setValue(newValueForKey(it.key()));
   }
 }
 
 // deleting entries during iteration:
 for (TByteLongIterator it = map.iterator();
      it.hasNext();) {
   it.advance();
   if (satisfiesCondition(it.key()) {
     it.remove();
   }
 }
 
 // faster iteration by avoiding hasNext():
 TByteLongIterator 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
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected 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

    Constructors
    Constructor
    Description
    Creates an iterator over the specified map
  • Method Summary

    Modifier and Type
    Method
    Description
    void
    Moves the iterator forward to the next entry in the underlying map.
    boolean
    Returns true if the iterator can be advanced past its current location.
    byte
    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
    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
    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 Details

    • _hash

      protected final TPrimitiveHash _hash
      the collection on which this iterator operates.
    • _expectedSize

      protected int _expectedSize
      the number of elements this iterator believes are in the data structure it accesses.
    • _index

      protected int _index
      the index used for iteration.
  • Constructor Details

    • TByteLongIterator

      public TByteLongIterator(TByteLongHashMap map)
      Creates an iterator over the specified map
  • Method Details

    • 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 byte 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.
    • 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.
    • hasNext

      public boolean hasNext()
      Returns true if the iterator can be advanced past its current location.
      Returns:
      a boolean value
    • 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.