Interface Map.Entry<K,V> 
- Type Parameters:
- K- the type of the key
- V- the type of the value
- All Known Implementing Classes:
- AbstractMap.SimpleEntry,- AbstractMap.SimpleImmutableEntry
setValue method is
 implemented. The Entry may be independent of any map, or it may represent
 an entry of the entry-set view of a map.
 
 An Entry maintains a connection to its underlying map if the Entry was obtained by
 iterating the Map.entrySet() view of a map, either explicitly by using an
 Iterator or implicitly via the enhanced for statement. This connection
 to the backing map is valid only during iteration of the entry-set view. During
 the iteration, if supported by the backing map, a change to an Entry's value via
 the setValue method will be visible in the backing map.
 The behavior of such an Entry is undefined outside of iteration of the map's entry-set
 view. It is also undefined if the backing map has been modified after the Entry was
 returned by the iterator, except through the setValue method. In addition,
 a change to the value of a mapping in the backing map might or might not be
 visible in the corresponding Entry of the entry-set view.
 
 An Entry may also be obtained from a map's entry-set view by other means, for
 example, using the
 parallelStream,
 stream,
 spliterator methods,
 any of the
 toArray overloads,
 or by copying the entry-set view into another collection. It is unspecified whether
 the obtained Entry instances are connected to the underlying map, whether changes
 to such an Entry will affect the underlying the map and vice-versa, and whether
 such an Entry supports the optional setValue method.
 
 In addition, an Entry may be obtained directly from a map, for example via calls
 to methods directly on the NavigableMap interface. An entry thus obtained
 is generally not connected to the map and is an unmodifiable snapshot of the mapping
 as of the time of the call. Such an Entry also does not generally support the
 setValue method.
 
 An Entry obtained by direct construction of the AbstractMap.SimpleEntry
 or AbstractMap.SimpleImmutableEntry classes or from a call to the
 Map.entry or Map.Entry.copyOf methods
 is not connected to any map.
- API Note:
- The exact behavior of Entry instances obtained from a map's entry-set view other than
 via iteration varies across different map implementations; some are connected to the
 backing map, and some are not. To guarantee that an Entry is disconnected from its
 backing map, use the copyOfmethod. For example, the following creates a snapshot of a map's entries that is guaranteed not to change even if the original map is modified:var entries = map.entrySet().stream().map(Map.Entry::copyOf).toList()
- Since:
- 1.2
- See Also:
- 
Method SummaryModifier and TypeMethodDescriptionstatic <K extends Comparable<? super K>, V>
 Comparator<Map.Entry<K, V>> Returns a comparator that comparesMap.Entryin natural order on key.static <K,V> Comparator <Map.Entry<K, V>> comparingByKey(Comparator<? super K> cmp) Returns a comparator that comparesMap.Entryby key using the givenComparator.static <K, V extends Comparable<? super V>>
 Comparator<Map.Entry<K, V>> Returns a comparator that comparesMap.Entryin natural order on value.static <K,V> Comparator <Map.Entry<K, V>> comparingByValue(Comparator<? super V> cmp) Returns a comparator that comparesMap.Entryby value using the givenComparator.static <K,V> Map.Entry <K, V> Returns a copy of the givenMap.Entry.booleanCompares the specified object with this entry for equality.getKey()Returns the key corresponding to this entry.getValue()Returns the value corresponding to this entry.inthashCode()Returns the hash code value for this map entry.Replaces the value corresponding to this entry with the specified value (optional operation).
- 
Method Details- 
getKeyK getKey()Returns the key corresponding to this entry.- Returns:
- 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.
 
- 
getValueV getValue()Returns the value corresponding to this entry. If the mapping has been removed from the backing map (by the iterator'sremoveoperation), the results of this call are undefined.- Returns:
- 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.
 
- 
setValueReplaces 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'sremoveoperation).- Parameters:
- value- new value to be stored in this entry
- Returns:
- old value corresponding to the entry
- Throws:
- UnsupportedOperationException- if the- putoperation 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.
 
- 
equalsCompares the specified object with this entry for equality. Returnstrueif the given object is also a map entry and the two entries represent the same mapping. More formally, two entriese1ande2represent the same mapping if(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 theequalsmethod works properly across different implementations of theMap.Entryinterface.
- 
hashCodeint hashCode()Returns the hash code value for this map entry. The hash code of a map entryeis defined to be:(e.getKey()==null ? 0 : e.getKey().hashCode()) ^ (e.getValue()==null ? 0 : e.getValue().hashCode())This ensures thate1.equals(e2)implies thate1.hashCode()==e2.hashCode()for any two Entriese1ande2, as required by the general contract ofObject.hashCode.
- 
comparingByKeyReturns a comparator that comparesMap.Entryin natural order on key.The returned comparator is serializable and throws NullPointerExceptionwhen comparing an entry with a null key.- Type Parameters:
- K- the- Comparabletype of then map keys
- V- the type of the map values
- Returns:
- a comparator that compares Map.Entryin natural order on key.
- Since:
- 1.8
- See Also:
 
- 
comparingByValueReturns a comparator that comparesMap.Entryin natural order on value.The returned comparator is serializable and throws NullPointerExceptionwhen comparing an entry with null values.- Type Parameters:
- K- the type of the map keys
- V- the- Comparabletype of the map values
- Returns:
- a comparator that compares Map.Entryin natural order on value.
- Since:
- 1.8
- See Also:
 
- 
comparingByKeyReturns a comparator that comparesMap.Entryby key using the givenComparator.The returned comparator is serializable if the specified comparator is also serializable. - Type Parameters:
- K- the type of the map keys
- V- the type of the map values
- Parameters:
- cmp- the key- Comparator
- Returns:
- a comparator that compares Map.Entryby the key.
- Since:
- 1.8
 
- 
comparingByValueReturns a comparator that comparesMap.Entryby value using the givenComparator.The returned comparator is serializable if the specified comparator is also serializable. - Type Parameters:
- K- the type of the map keys
- V- the type of the map values
- Parameters:
- cmp- the value- Comparator
- Returns:
- a comparator that compares Map.Entryby the value.
- Since:
- 1.8
 
- 
copyOfReturns a copy of the givenMap.Entry. The returned instance is not associated with any map. The returned instance has the same characteristics as instances returned by theMap::entrymethod.- API Note:
- An instance obtained from a map's entry-set view has a connection to that map.
 The copyOfmethod may be used to create aMap.Entryinstance, containing the same key and value, that is independent of any map.
- Implementation Note:
- If the given entry was obtained from a call to copyOforMap::entry, callingcopyOfwill generally not create another copy.
- Type Parameters:
- K- the type of the key
- V- the type of the value
- Parameters:
- e- the entry to be copied
- Returns:
- a map entry equal to the given entry
- Throws:
- NullPointerException- if e is null or if either of its key or value is null
- Since:
- 17
 
 
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