public interface

MapIterator

implements Iterator<E>
org.apache.commons.collections.MapIterator
Known Indirect Subclasses

Class Overview

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);
 }

Summary

Public Methods
abstract Object getKey()
Gets the current key, which is the key returned by the last call to next().
abstract Object getValue()
Gets the current value, which is the value associated with the last key returned by next().
abstract boolean hasNext()
Checks to see if there are more entries still to be iterated.
abstract Object next()
Gets the next key from the Map.
abstract void remove()
Removes the last returned key from the underlying Map (optional operation).
abstract Object setValue(Object value)
Sets the value associated with the current key (optional operation).
[Expand]
Inherited Methods
From interface java.util.Iterator

Public Methods

public abstract 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

public abstract 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

public abstract boolean hasNext ()

Checks to see if there are more entries still to be iterated.

Returns
  • true if the iterator has more elements

public abstract Object next ()

Gets the next key from the Map.

Returns
  • the next key in the iteration
Throws
NoSuchElementException if the iteration is finished

public abstract void remove ()

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

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

Throws
UnsupportedOperationException if remove is not supported by the map
IllegalStateException if next() has not yet been called
IllegalStateException if remove() has already been called since the last call to next()

public abstract 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
IllegalStateException if remove() has been called since the last call to next()