Apache Commons Collections 4.4 · org.apache.commons.collections4.MapIterator

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<String,Integer> it = map.mapIterator();
while (it.hasNext()) {
  String key = it.next();
  Integer value = it.getValue();
  it.setValue(value + 1);
}

Method Summary

Modifier and Type	Method and Description
public K	Returns: the current key getKey() Gets the current key, which is the key returned by the last call to `next()`.
public V	Returns: the current value getValue() Gets the current value, which is the value associated with the last key returned by `next()`.
public boolean	Returns: `true` if the iterator has more elements hasNext() Redeclares java.util.Iterator.hasNext. Checks to see if there are more entries still to be iterated.
public K	Returns: the next key in the iteration next() Redeclares java.util.Iterator.next. Gets the next key from the `Map`.
public void	remove() Redeclares as abstract: java.util.Iterator.remove. Removes the last returned key from the underlying `Map` (optional operation).
public V	Returns: the previous value setValue(V the new value value) Sets the value associated with the current key (optional operation).

Inherited from java.util.Iterator:: forEachRemaining

Method Detail

getKey back to summary

getKey	back to summary
public K getKey() Gets the current key, which is the key returned by the last call to `next()`. Returns:K the current key Exceptions IllegalStateException: if `next()` has not yet been called

public K getKey()

Gets the current key, which is the key returned by the last call to next().

Returns:K

the current key

Exceptions

IllegalStateException:: if next() has not yet been called

getValue back to summary

getValue	back to summary
public V getValue() Gets the current value, which is the value associated with the last key returned by `next()`. Returns:V the current value Exceptions IllegalStateException: if `next()` has not yet been called

public V getValue()

Gets the current value, which is the value associated with the last key returned by next().

Returns:V

the current value

Exceptions

IllegalStateException:: if next() has not yet been called

hasNext back to summary

hasNext	back to summary
public boolean hasNext() Redeclares java.util.Iterator.hasNext. Checks to see if there are more entries still to be iterated. Returns:boolean `true` if the iterator has more elements Annotations @Override

public boolean hasNext()

Redeclares java.util.Iterator.hasNext.

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

Returns:boolean

true if the iterator has more elements

Annotations

@Override

next back to summary

next	back to summary
public K next() Redeclares java.util.Iterator.next. Gets the next key from the `Map`. Returns:K the next key in the iteration Annotations @Override Exceptions NoSuchElementException: if the iteration is finished

public K next()

Redeclares java.util.Iterator.next.

Gets the next key from the Map.

Returns:K

the next key in the iteration

Annotations

@Override

Exceptions

NoSuchElementException:: if the iteration is finished

remove back to summary

remove	back to summary
public void remove() Redeclares as abstract: java.util.Iterator.remove. Removes the last returned key from the underlying `Map` (optional operation). This method can be called once per call to `next()`. Annotations @Override Exceptions UnsupportedOperationException: if remove is not supported by the map IllegalStateException: if `next()` has not yet been called if `remove()` has already been called since the last call to `next()`

public void remove()

Redeclares as abstract: java.util.Iterator.remove.

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

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

Annotations

@Override

Exceptions

UnsupportedOperationException:

if remove is not supported by the map

IllegalStateException:

if next() has not yet been called
if remove() has already been called since the last call to next()

setValue back to summary

setValue	back to summary
public V setValue(V value) Sets the value associated with the current key (optional operation). Parameters value:V the new value Returns:V the previous value Exceptions UnsupportedOperationException: if setValue is not supported by the map IllegalStateException: if `next()` has not yet been called if `remove()` has been called since the last call to `next()`

public V setValue(V value)

Sets the value associated with the current key (optional operation).

Parameters

value:V: the new value

Returns:V

the previous value

Exceptions

UnsupportedOperationException:

if setValue is not supported by the map

IllegalStateException:

if next() has not yet been called
if remove() has been called since the last call to next()

public Interface MapIterator<K, V>

Method Summary

Method Detail