public
static
interface
Map.Entry
| java.util.Map.Entry<K, V> |
 Known Indirect Subclasses
AbstractMap.SimpleEntry<K, V>,
AbstractMap.SimpleImmutableEntry<K, V>
|
A map entry (key-value pair). The Map.entrySet method returns
a collection-view of the map, whose elements are of this class. The
only way to obtain a reference to a map entry is from the
iterator of this collection-view. These Map.Entry objects are
valid only for the duration of the iteration; more formally,
the behavior of a map entry is undefined if the backing map has been
modified after the entry was returned by the iterator, except through
the setValue operation on the map entry.
See also:
Public methods | |
|---|---|
static
<K, V>
Comparator<Entry<K, V>>
|
comparingByKey(Comparator<? super K> cmp)
Returns a comparator that compares |
static
<K extends Comparable<? super K>, V>
Comparator<Entry<K, V>>
|
comparingByKey()
Returns a comparator that compares |
static
<K, V>
Comparator<Entry<K, V>>
|
comparingByValue(Comparator<? super V> cmp)
Returns a comparator that compares |
static
<K, V extends Comparable<? super V>>
Comparator<Entry<K, V>>
|
comparingByValue()
Returns a comparator that compares |
abstract
boolean
|
equals(Object o)
Compares the specified object with this entry for equality. |
abstract
K
|
getKey()
Returns the key corresponding to this entry. |
abstract
V
|
getValue()
Returns the value corresponding to this entry. |
abstract
int
|
hashCode()
Returns the hash code value for this map entry. |
abstract
V
|
setValue(V value)
Replaces the value corresponding to this entry with the specified value (optional operation). |
Comparator<Entry<K, V>> comparingByKey (Comparator<? super K> cmp)
Returns a comparator that compares Map.Entry by key using the given
Comparator.
The returned comparator is serializable if the specified comparator is also serializable.
| Parameters | |
|---|---|
cmp |
Comparator:
the key Comparator |
| Returns | |
|---|---|
Comparator<Entry<K, V>> |
a comparator that compares Map.Entry by the key. |
Comparator<Entry<K, V>> comparingByKey ()
Returns a comparator that compares Map.Entry in natural order on key.
The returned comparator is serializable and throws NullPointerException when comparing an entry with a null key.
| Returns | |
|---|---|
Comparator<Entry<K, V>> |
a comparator that compares Map.Entry in natural order on key. |
See also:
Comparator<Entry<K, V>> comparingByValue (Comparator<? super V> cmp)
Returns a comparator that compares Map.Entry by value using the given
Comparator.
The returned comparator is serializable if the specified comparator is also serializable.
| Parameters | |
|---|---|
cmp |
Comparator:
the value Comparator |
| Returns | |
|---|---|
Comparator<Entry<K, V>> |
a comparator that compares Map.Entry by the value. |
Comparator<Entry<K, V>> comparingByValue ()
Returns a comparator that compares Map.Entry in natural order on value.
The returned comparator is serializable and throws NullPointerException when comparing an entry with null values.
| Returns | |
|---|---|
Comparator<Entry<K, V>> |
a comparator that compares Map.Entry in natural order on value. |
See also:
boolean equals (Object o)
Compares the specified object with this entry for equality.
Returns true if the given object is also a map entry and
the two entries represent the same mapping. More formally, two
entries e1 and e2 represent the same mapping
if
Developers
(e1.getKey()==null ?
e2.getKey()==null : e1.getKey().equals(e2.getKey())) &&
(e1.getValue()==null ?
e2.getValue()==null : e1.getValue().equals(e2.getValue()))
This ensures that the equals method works properly across
different implementations of the Map.Entry interface.
| Parameters | |
|---|---|
o |
Object:
object to be compared for equality with this map entry |
| Returns | |
|---|---|
boolean |
true if the specified object is equal to this map
entry
|
K getKey ()
Returns the key corresponding to this entry.
| Returns | |
|---|---|
K |
the key corresponding to this entry |
| Throws | |
|---|---|
IllegalStateException |
implementations may, but are not required to, throw this exception if the entry has been removed from the backing map. |
V getValue ()
Returns the value corresponding to this entry. If the mapping
has been removed from the backing map (by the iterator's
remove operation), the results of this call are undefined.
| Returns | |
|---|---|
V |
the value corresponding to this entry |
| Throws | |
|---|---|
IllegalStateException |
implementations may, but are not required to, throw this exception if the entry has been removed from the backing map. |
int hashCode ()
Returns the hash code value for this map entry. The hash code
of a map entry e is defined to be:
(e.getKey()==null ? 0 : e.getKey().hashCode()) ^
(e.getValue()==null ? 0 : e.getValue().hashCode())
This ensures that e1.equals(e2) implies that
e1.hashCode()==e2.hashCode() for any two Entries
e1 and e2, as required by the general
contract of Object.hashCode.
| Returns | |
|---|---|
int |
the hash code value for this map entry |
See also:
V setValue (V value)
Replaces the value corresponding to this entry with the specified
value (optional operation). (Writes through to the map.) The
behavior of this call is undefined if the mapping has already been
removed from the map (by the iterator's remove operation).
| Parameters | |
|---|---|
value |
V:
new value to be stored in this entry |
| Returns | |
|---|---|
V |
old value corresponding to the entry |
| Throws | |
|---|---|
UnsupportedOperationException |
if the put operation
is not supported by the backing map |
ClassCastException |
if the class of the specified value prevents it from being stored in the backing map |
NullPointerException |
if the backing map does not permit null values, and the specified value is null |
IllegalArgumentException |
if some property of this value prevents it from being stored in the backing map |
IllegalStateException |
implementations may, but are not required to, throw this exception if the entry has been removed from the backing map. |