Package it.unimi.dsi.fastutil.objects

Class Reference2ReferenceFunctions.EmptyFunction<K,V>

java.lang.Object

it.unimi.dsi.fastutil.objects.AbstractReference2ReferenceFunction<K,V>

it.unimi.dsi.fastutil.objects.Reference2ReferenceFunctions.EmptyFunction<K,V>

All Implemented Interfaces:

Function<K,V>, Reference2ReferenceFunction<K,V>, Serializable, Cloneable, Function<K,V>

Direct Known Subclasses:

Reference2ReferenceMaps.EmptyMap

Enclosing class:

Reference2ReferenceFunctions

public static class Reference2ReferenceFunctions.EmptyFunction<K,V>
extends AbstractReference2ReferenceFunction<K,V>
implements Serializable, Cloneable

An immutable class representing an empty type-specific function.

This class may be useful to implement your own in case you subclass a type-specific function.

See Also:

• Serialized Form

Method Summary

Modifier and Type	Method	Description
void	clear()	Removes all associations from this function (optional operation).
Object	clone()
boolean	containsKey(Object k)	Returns true if this function contains a mapping for the specified key.
V	defaultReturnValue()	Gets the default return value.
void	defaultReturnValue(V defRetValue)	Sets the default return value (optional operation).
boolean	equals(Object o)
V	get(Object k)	Returns the value to which the given key is mapped.
V	getOrDefault(Object k, V defaultValue)	Returns the value associated by this function to the specified key, or give the specified value if not present.
int	hashCode()
int	size()	Returns the intended number of keys in this function, or -1 if no such number exists.
String	toString()

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface it.unimi.dsi.fastutil.Function

apply

Methods inherited from interface java.util.function.Function

andThen, compose

Methods inherited from interface it.unimi.dsi.fastutil.objects.Reference2ReferenceFunction

andThenByte, andThenChar, andThenDouble, andThenFloat, andThenInt, andThenLong, andThenObject, andThenReference, andThenShort, composeByte, composeChar, composeDouble, composeFloat, composeInt, composeLong, composeObject, composeReference, composeShort, put, remove

Method Details

get

public V get(Object k)

Description copied from interface: Reference2ReferenceFunction

Returns the value to which the given key is mapped.

Specified by:

get in interface Function<K,V>

Specified by:

get in interface Reference2ReferenceFunction<K,V>

Parameters:

k - the key.

Returns:

the corresponding value, or the default return value if no value was present for the given key.

See Also:

• Function.get(Object)

getOrDefault

public V getOrDefault(Object k,
 V defaultValue)

Description copied from interface: Reference2ReferenceFunction

Returns the value associated by this function to the specified key, or give the specified value if not present.

Specified by:

getOrDefault in interface Function<K,V>

Specified by:

getOrDefault in interface Reference2ReferenceFunction<K,V>

Parameters:

k - the key.

defaultValue - the value to return if not present.

Returns:

the corresponding value, or defaultValue if no value was present for the given key.

See Also:

• Function.getOrDefault(Object, Object)

containsKey

public boolean containsKey(Object k)

Description copied from interface: Function

Returns true if this function contains a mapping for the specified key.

Note that for some kind of functions (e.g., hashes) this method will always return true. This default implementation, in particular, always return true.

Specified by:

containsKey in interface Function<K,V>

Parameters:

k - the key.

Returns:

true if this function associates a value to key.

See Also:

• Map.containsKey(Object)

defaultReturnValue

public V defaultReturnValue()

Description copied from interface: Reference2ReferenceFunction

Gets the default return value.

This default implementation just return the default null value of the type (null for objects, 0 for scalars, false for Booleans).

Specified by:

defaultReturnValue in interface Reference2ReferenceFunction<K,V>

Overrides:

defaultReturnValue in class AbstractReference2ReferenceFunction<K,V>

Returns:

the current default return value.

defaultReturnValue

public void defaultReturnValue(V defRetValue)

Description copied from interface: Reference2ReferenceFunction

Sets the default return value (optional operation). This value must be returned by type-specific versions of get(), put() and remove() to denote that the map does not contain the specified key. It must be 0/false/null by default.

Specified by:

defaultReturnValue in interface Reference2ReferenceFunction<K,V>

Overrides:

defaultReturnValue in class AbstractReference2ReferenceFunction<K,V>

Parameters:

defRetValue - the new default return value.

See Also:

• Reference2ReferenceFunction.defaultReturnValue()

size

public int size()

Description copied from interface: Function

Returns the intended number of keys in this function, or -1 if no such number exists.

Most function implementations will have some knowledge of the intended number of keys in their domain. In some cases, however, this might not be possible. This default implementation, in particular, returns -1.

Specified by:

size in interface Function<K,V>

Returns:

the intended number of keys in this function, or -1 if that number is not available.

clear

public void clear()

Description copied from interface: Function

Removes all associations from this function (optional operation).

Specified by:

clear in interface Function<K,V>

See Also:

• Map.clear()

clone

public Object clone()

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object o)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object