java.util
Interface Map.Entry<K,V>

Enclosing interface:
Map sample code for java.util.Map definition code for java.util.Map <K,V>

public static interface Map.Entry<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.

Since:
1.2
See Also:
Map.entrySet() sample code for java.util.Map.entrySet() definition code for java.util.Map.entrySet()

Method Summary
 boolean equals sample code for java.util.Map.Entry.equals(java.lang.Object) definition code for java.util.Map.Entry.equals(java.lang.Object) (Object sample code for java.lang.Object definition code for java.lang.Object  o)
          Compares the specified object with this entry for equality.
 K getKey sample code for java.util.Map.Entry.getKey() definition code for java.util.Map.Entry.getKey() ()
          Returns the key corresponding to this entry.
 V getValue sample code for java.util.Map.Entry.getValue() definition code for java.util.Map.Entry.getValue() ()
          Returns the value corresponding to this entry.
 int hashCode sample code for java.util.Map.Entry.hashCode() definition code for java.util.Map.Entry.hashCode() ()
          Returns the hash code value for this map entry.
 V setValue sample code for java.util.Map.Entry.setValue(V) definition code for java.util.Map.Entry.setValue(V) (V value)
          Replaces the value corresponding to this entry with the specified value (optional operation).
 

Method Detail

getKey sample code for java.util.Map.Entry.getKey() definition code for java.util.Map.Entry.getKey()

K getKey()
Returns the key corresponding to this entry.

Returns:
the key corresponding to this entry.
Throws:
IllegalStateException sample code for java.lang.IllegalStateException definition code for java.lang.IllegalStateException - implementations may, but are not required to, throw this exception if the entry has been removed from the backing map

getValue sample code for java.util.Map.Entry.getValue() definition code for java.util.Map.Entry.getValue()

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:
the value corresponding to this entry.
Throws:
IllegalStateException sample code for java.lang.IllegalStateException definition code for java.lang.IllegalStateException - implementations may, but are not required to, throw this exception if the entry has been removed from the backing map

setValue sample code for java.util.Map.Entry.setValue(V) definition code for java.util.Map.Entry.setValue(V)

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 - new value to be stored in this entry.
Returns:
old value corresponding to the entry.
Throws:
UnsupportedOperationException sample code for java.lang.UnsupportedOperationException definition code for java.lang.UnsupportedOperationException - if the put operation is not supported by the backing map.
ClassCastException sample code for java.lang.ClassCastException definition code for java.lang.ClassCastException - if the class of the specified value prevents it from being stored in the backing map.
IllegalArgumentException sample code for java.lang.IllegalArgumentException definition code for java.lang.IllegalArgumentException - if some aspect of this value prevents it from being stored in the backing map.
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - if the backing map does not permit null values, and the specified value is null.
IllegalStateException sample code for java.lang.IllegalStateException definition code for java.lang.IllegalStateException - implementations may, but are not required to, throw this exception if the entry has been removed from the backing map

equals sample code for java.util.Map.Entry.equals(java.lang.Object) definition code for java.util.Map.Entry.equals(java.lang.Object)

boolean equals(Object sample code for java.lang.Object definition code for java.lang.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
     (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.

Overrides:
equals sample code for java.lang.Object.equals(java.lang.Object) definition code for java.lang.Object.equals(java.lang.Object) in class Object sample code for java.lang.Object definition code for java.lang.Object
Parameters:
o - object to be compared for equality with this map entry.
Returns:
true if the specified object is equal to this map entry.
See Also:
Object.hashCode() sample code for java.lang.Object.hashCode() definition code for java.lang.Object.hashCode() , Hashtable sample code for java.util.Hashtable definition code for java.util.Hashtable

hashCode sample code for java.util.Map.Entry.hashCode() definition code for java.util.Map.Entry.hashCode()

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.

Overrides:
hashCode sample code for java.lang.Object.hashCode() definition code for java.lang.Object.hashCode() in class Object sample code for java.lang.Object definition code for java.lang.Object
Returns:
the hash code value for this map entry.
See Also:
Object.hashCode() sample code for java.lang.Object.hashCode() definition code for java.lang.Object.hashCode() , Object.equals(Object) sample code for java.lang.Object.equals(java.lang.Object) definition code for java.lang.Object.equals(java.lang.Object) , equals(Object) sample code for java.util.Map.Entry.equals(java.lang.Object) definition code for java.util.Map.Entry.equals(java.lang.Object)