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java.lang.Object | +----java.util.Dictionary
Dictionary
class is the abstract parent of any
class, such as Hashtable
, which maps keys to values.
Any non-null
object can be used as a key and as a value.
As a rule, the equals
method should be used by
implementations of this class to decide if two keys are the same.
key
to the specified
value
in this dictionary.
key
(and its corresponding
value
) from this dictionary.
public Dictionary()
public abstract int size()
public abstract boolean isEmpty()
true
if this dictionary maps no keys to values;
false
otherwise.
public abstract Enumeration keys()
public abstract Enumeration elements()
public abstract Object get(Object key)
null
if the key is not mapped to any value in
this dictionary.
public abstract Object put(Object key, Object value)
key
to the specified
value
in this dictionary. Neither the key nor the
value can be null
.
The value
can be retrieved by calling the
get
method with a key
that is equal to
the original key
.
key
was mapped
in this dictionary, or null
if the key did not
have a previous mapping.
key
or
value
is null
.
public abstract Object remove(Object key)
key
(and its corresponding
value
) from this dictionary. This method does nothing
if the key
is not in this dictionary.
key
had been mapped in this
dictionary, or null
if the key did not have a
mapping.
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