K
- the type of the keys in the mapV
- the type of the values in the mappublic interface MapIterator<K,V>
extends java.util.Iterator<K>
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()
.
MapIteratorit = map.mapIterator(); while (it.hasNext()) { String key = it.next(); Integer value = it.getValue(); it.setValue(value + 1); }
Modifier and Type | Method and Description |
---|---|
K |
getKey()
Gets the current key, which is the key returned by the last call
to
next() . |
V |
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.
|
K |
next()
Gets the next key from the
Map . |
void |
remove()
Removes the last returned key from the underlying
Map (optional operation). |
V |
setValue(V value)
Sets the value associated with the current key (optional operation).
|
boolean hasNext()
hasNext
in interface java.util.Iterator<K>
true
if the iterator has more elementsK next()
Map
.next
in interface java.util.Iterator<K>
java.util.NoSuchElementException
- if the iteration is finishedK getKey()
next()
.java.lang.IllegalStateException
- if next()
has not yet been calledV getValue()
next()
.java.lang.IllegalStateException
- if next()
has not yet been calledvoid remove()
Map
(optional operation).
This method can be called once per call to next()
.
remove
in interface java.util.Iterator<K>
java.lang.UnsupportedOperationException
- if remove is not supported by the mapjava.lang.IllegalStateException
- if next()
has not yet been calledjava.lang.IllegalStateException
- if remove()
has already been called
since the last call to next()
V setValue(V value)
value
- the new valuejava.lang.UnsupportedOperationException
- if setValue is not supported by the mapjava.lang.IllegalStateException
- if next()
has not yet been calledjava.lang.IllegalStateException
- if remove()
has been called since the
last call to next()
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