public abstract class AbstractMap extends Object implements Map
Map
interface. This
implementation does not support adding. A subclass must implement the
abstract method entrySet().Modifier | Constructor and Description |
---|---|
protected |
AbstractMap()
Constructs a new instance of this
AbstractMap . |
Modifier and Type | Method and Description |
---|---|
void |
clear()
Removes all elements from this map, leaving it empty.
|
protected Object |
clone()
Returns a new instance of the same class as this instance, whose slots
have been filled in with the values of the slots of this instance.
|
boolean |
containsKey(Object key)
Returns whether this map contains the specified key.
|
boolean |
containsValue(Object value)
Returns whether this map contains the specified value.
|
abstract Set |
entrySet()
Returns a set containing all of the mappings in this map.
|
boolean |
equals(Object object)
Compares the specified object to this instance, and returns
true
if the specified object is a map and both maps contain the same mappings. |
Object |
get(Object key)
Returns the value of the mapping with the specified key.
|
int |
hashCode()
Returns the hash code for this object.
|
boolean |
isEmpty()
Returns whether this map is empty.
|
Set |
keySet()
Returns a set of the keys contained in this map.
|
Object |
put(Object key,
Object value)
Maps the specified key to the specified value.
|
void |
putAll(Map map)
Copies every mapping in the specified map to this map.
|
Object |
remove(Object key)
Removes a mapping with the specified key from this Map.
|
int |
size()
Returns the number of elements in this map.
|
String |
toString()
Returns the string representation of this map.
|
Collection |
values()
Returns a collection of the values contained in this map.
|
protected AbstractMap()
AbstractMap
.public void clear()
clear
in interface Map
UnsupportedOperationException
- if removing from this map is not supported.isEmpty()
,
size()
public boolean containsKey(Object key)
containsKey
in interface Map
key
- the key to search for.true
if this map contains the specified key,
false
otherwise.public boolean containsValue(Object value)
containsValue
in interface Map
value
- the value to search for.true
if this map contains the specified value,
false
otherwise.public abstract Set entrySet()
Map.Entry
. As the set is backed by this map,
changes in one will be reflected in the other.public boolean equals(Object object)
true
if the specified object is a map and both maps contain the same mappings.equals
in interface Map
equals
in class Object
object
- the object to compare with this object.true
if the object is the same as this object,
and false
if it is different from this object.hashCode()
,
entrySet()
public int hashCode()
hashCode
in interface Map
hashCode
in class Object
equals(Object)
public boolean isEmpty()
public Set keySet()
public Object put(Object key, Object value)
put
in interface Map
key
- the key.value
- the value.null
if there was no mapping.UnsupportedOperationException
- if adding to this map is not supported.ClassCastException
- if the class of the key or value is inappropriate for this
map.IllegalArgumentException
- if the key or value cannot be added to this map.NullPointerException
- if the key or value is null
and this Map does not
support null
keys or values.public void putAll(Map map)
putAll
in interface Map
map
- the map to copy mappings from.UnsupportedOperationException
- if adding to this map is not supported.ClassCastException
- if the class of a key or value is inappropriate for this
map.IllegalArgumentException
- if a key or value cannot be added to this map.NullPointerException
- if a key or value is null
and this map does not
support null
keys or values.public Object remove(Object key)
remove
in interface Map
key
- the key of the mapping to remove.null
if no mapping
for the specified key was found.UnsupportedOperationException
- if removing from this map is not supported.public int size()
public String toString()
public Collection values()
This method returns a collection which is the subclass of
AbstractCollection. The iterator method of this subclass returns a
"wrapper object" over the iterator of map's entrySet(). The size
method wraps the map's size method and the contains
method wraps
the map's containsValue method.
The collection is created when this method is called for the first time and returned in response to all subsequent calls. This method may return different collections when multiple concurrent calls occur to this method, since no synchronization is performed.
protected Object clone() throws CloneNotSupportedException
clone
in class Object
CloneNotSupportedException
- if the receiver's class does not implement the interface
Cloneable
.