Summary of Classes and Interfaces - Absolute Java - page 1183

public int hashCode()
Returns the hash code value for the calling object. The hash code of a map is defi ned to be the
sum of the hashCodes of each entry in the map's entrySet view.
public boolean isEmpty()
Returns true if the calling object is empty; otherwise returns false .
public int size()
Returns the number of (key, value) mappings in the calling object.
public Collection<V> values()
Returns a collection view consisting of all values in the map. Changes to the map are refl ected in
the collection and vice-versa.
OPTIONAL METHODS
The following methods are optional, which means they still must be implemented, but the
implementation can simply throw an UnsupportedOperationException if, for some reason,
you do not want to give them a “real” implementation. An UnsupportedOperationException
is a RunTimeException and so is not required to be caught or declared in a throws clause.
public V put(K key, V value) (Optional)
Associates key to value in the map. If key was associated with an existing value, then the old
value is overwritten and returned. Otherwise null is returned.
Throws:
ClassCastException if the type of key or value is incompatible with the type for this
map (optional).
NullPointerException if the key or value is null and this map does not permit null keys
or values (optional).
IllegalArgumentException if some aspect of the key or value prevents it from being stored
in this map (optional).
UnsupportedOperationException if the put operation is not supported by this
map (optional).
public void putAll(Map<? extends K,? extends V> mapToAdd) (Optional)
Adds all mappings of mapToAdd into the calling object's map.
Throws:
ClassCastException if any type of key or value of mapToAdd is incompatible with the
type for this map (optional).
NullPointerException if mapToAdd is null or any key or value of mapToAdd is null and
this map does not permit null keys or values (optional).
IllegalArgumentException if some aspect of the key or value from mapToAdd prevents it
from being stored in this map (optional).
UnsupportedOperationException if the putAll operation is not supported by this
map (optional).