Package com.espertech.esper.common.internal.collection.apachecommons

Interface MapIterator

All Superinterfaces:
Iterator
All Known Implementing Classes:
AbstractHashedMap.HashMapIterator, EmptyMapIterator
public interface MapIterator extends Iterator
Defines an iterator that operates over a Map.

This iterator is a special version designed for maps. It can be more efficient to use this rather than an entry set iterator where the option is available, and it is certainly more convenient.

A map that provides this interface may not hold the data internally using Map Entry objects, thus this interface can avoid lots of object creation.

In use, this iterator iterates through the keys in the map. After each call to next(), the getValue() method provides direct access to the value. The value can also be set using setValue(). 

 MapIterator it = map.mapIterator();
 while (it.hasNext()) {
   Object key = it.next();
   Object value = it.getValue();
   it.setValue(newValue);
 }
Since:
Commons Collections 3.0
Version:
$Revision$ $Date$
Author:
Stephen Colebourne

  • Method Summary

    Modifier and Type
    Method
    Description
    Object
    getKey()
    Gets the current key, which is the key returned by the last call to next().
    Object
    getValue()
    Gets the current value, which is the value associated with the last key returned by next().
    boolean
    hasNext()
    Checks to see if there are more entries still to be iterated.
    Object
    next()
    Gets the next key from the Map.
    void
    remove()
    Removes the last returned key from the underlying Map (optional operation).
    Object
    setValue(Object value)
    Sets the value associated with the current key (optional operation).

    Methods inherited from interface java.util.Iterator

    forEachRemaining

  • Method Details

    • hasNext

      boolean hasNext()
      Checks to see if there are more entries still to be iterated.
      Specified by:
      hasNext in interface Iterator
      Returns:
      true if the iterator has more elements

    • next

      Object next()
      Gets the next key from the Map.
      Specified by:
      next in interface Iterator
      Returns:
      the next key in the iteration
      Throws:
      NoSuchElementException - if the iteration is finished

    • getKey

      Object getKey()
      Gets the current key, which is the key returned by the last call to next().
      Returns:
      the current key
      Throws:
      IllegalStateException - if next() has not yet been called

    • getValue

      Object getValue()
      Gets the current value, which is the value associated with the last key returned by next().
      Returns:
      the current value
      Throws:
      IllegalStateException - if next() has not yet been called

    • remove

      void remove()
      Removes the last returned key from the underlying Map (optional operation).

      This method can be called once per call to next().

      Specified by:
      remove in interface Iterator
      Throws:
      UnsupportedOperationException - if remove is not supported by the map
      IllegalStateException - if next() has not yet been called or if remove() has already been called since the last call to next()

    • setValue

      Object setValue(Object value)
      Sets the value associated with the current key (optional operation).
      Parameters:
      value - the new value
      Returns:
      the previous value
      Throws:
      UnsupportedOperationException - if setValue is not supported by the map
      IllegalStateException - if next() has not yet been called or if remove() has been called since the last call to next()