org.apache.commons.collections

Interface MapIterator

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: 155406 $ $Date: 2005-02-26 12:55:26 +0000 (Sat, 26 Feb 2005) $

Author: Stephen Colebourne

Method Summary
ObjectgetKey()
Gets the current key, which is the key returned by the last call to next().
ObjectgetValue()
Gets the current value, which is the value associated with the last key returned by next().
booleanhasNext()
Checks to see if there are more entries still to be iterated.
Objectnext()
Gets the next key from the Map.
voidremove()
Removes the last returned key from the underlying Map (optional operation).
ObjectsetValue(Object value)
Sets the value associated with the current key (optional operation).

Method Detail

getKey

public 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

public 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

hasNext

public boolean hasNext()
Checks to see if there are more entries still to be iterated.

Returns: true if the iterator has more elements

next

public Object next()
Gets the next key from the Map.

Returns: the next key in the iteration

Throws: java.util.NoSuchElementException if the iteration is finished

remove

public 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()

setValue

public 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()

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