Interface java.util.Map.Entry
- Implementing Classes:
- TreeMap.Entry
- public abstract static interface Map.Entry
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 Iterator's own remove operation, or through the setValue operation
of Map.EntrySet returned by the Iterator.
- See Also:
- entrySet()
|
Method Summary
|
|
boolean
|
equals(java.lang.Object o)
Compares the specified Object with this Entry for equality.
|
|
java.lang.Object
|
getKey()
Returns the key corresponding to this Entry. |
|
java.lang.Object
|
getValue()
Returns the value corresponding to this Entry. |
|
int
|
hashCode()
Returns the hash code value for this Map. |
|
java.lang.Object
|
setValue(java.lang.Object value)
Replaces the value corresponding to this Entry with the specified
value (optional operation). |
getKey
public java.lang.Object getKey()
- Returns the key corresponding to this Entry.
getValue
public java.lang.Object 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.
setValue
public java.lang.Object setValue(java.lang.Object 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:
New
- value to be stored in this Entry.- Returns:
- old value corresponding to the Entry.
- Throws:
- UnsupportedOperationException - put operation is not
supported by the backing Map.
- ClassCastException - class of the specified value
prevents it from being stored in the backing Map.
- java.lang.IllegalArgumentException - some aspect of this value
prevents it from being stored in the backing Map.
- NullPointerException - the backing Map does not permit
null values, and the specified value is null.
equals
public boolean equals(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.
- Parameters:
o
- Object to be compared for equality with this Map.Entry.- Returns:
- true if the specified Object is equal to this Map.Entry.
- Overrides:
- equals in class java.lang.Object
hashCode
public 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 in class java.lang.Object
- See Also:
- hashCode(), equals(Object), equals(Object)