public static class Object2ReferenceFunctions.EmptyFunction<K,V> extends AbstractObject2ReferenceFunction<K,V> implements Serializable, Cloneable
This class may be useful to implement your own in case you subclass a type-specific function.
| Modifier and Type | Method and Description |
|---|---|
void |
clear() |
Object |
clone()
Creates and returns a copy of this object.
|
boolean |
containsKey(Object k) |
V |
defaultReturnValue()
Gets the default return value.
|
void |
defaultReturnValue(V defRetValue)
Sets the default return value (optional operation).
|
boolean |
equals(Object o)
Indicates whether some other object is "equal to" this one.
|
V |
get(Object k)
Returns the value to which the given key is mapped.
|
int |
hashCode()
Returns a hash code value for the object.
|
int |
size() |
String |
toString()
Returns a string representation of the object.
|
put, removepublic V get(Object k)
Object2ReferenceFunctionget in interface Object2ReferenceFunction<K,V>k - the key.Function.get(Object)public boolean containsKey(Object k)
public V defaultReturnValue()
Object2ReferenceFunction
This default implementation just return the default null value of the
type (null for objects, 0 for scalars, false for Booleans).
defaultReturnValue in interface Object2ReferenceFunction<K,V>defaultReturnValue in class AbstractObject2ReferenceFunction<K,V>public void defaultReturnValue(V defRetValue)
Object2ReferenceFunctionget(),
put() and remove() to denote that the map does not
contain the specified key. It must be 0/false/null by
default.defaultReturnValue in interface Object2ReferenceFunction<K,V>defaultReturnValue in class AbstractObject2ReferenceFunction<K,V>defRetValue - the new default return value.Object2ReferenceFunction.defaultReturnValue()public int size()
public void clear()
public Object clone()
java.lang.Objectx, the expression:
will be true, and that the expression:x.clone() != x
will bex.clone().getClass() == x.getClass()
true, but these are not absolute requirements.
While it is typically the case that:
will bex.clone().equals(x)
true, this is not an absolute requirement.
By convention, the returned object should be obtained by calling
super.clone. If a class and all of its superclasses (except
Object) obey this convention, it will be the case that
x.clone().getClass() == x.getClass().
By convention, the object returned by this method should be independent
of this object (which is being cloned). To achieve this independence,
it may be necessary to modify one or more fields of the object returned
by super.clone before returning it. Typically, this means
copying any mutable objects that comprise the internal "deep structure"
of the object being cloned and replacing the references to these
objects with references to the copies. If a class contains only
primitive fields or references to immutable objects, then it is usually
the case that no fields in the object returned by super.clone
need to be modified.
The method clone for class Object performs a
specific cloning operation. First, if the class of this object does
not implement the interface Cloneable, then a
CloneNotSupportedException is thrown. Note that all arrays
are considered to implement the interface Cloneable and that
the return type of the clone method of an array type T[]
is T[] where T is any reference or primitive type.
Otherwise, this method creates a new instance of the class of this
object and initializes all its fields with exactly the contents of
the corresponding fields of this object, as if by assignment; the
contents of the fields are not themselves cloned. Thus, this method
performs a "shallow copy" of this object, not a "deep copy" operation.
The class Object does not itself implement the interface
Cloneable, so calling the clone method on an object
whose class is Object will result in throwing an
exception at run time.
public int hashCode()
java.lang.ObjectHashMap.
The general contract of hashCode is:
hashCode method
must consistently return the same integer, provided no information
used in equals comparisons on the object is modified.
This integer need not remain consistent from one execution of an
application to another execution of the same application.
equals(Object)
method, then calling the hashCode method on each of
the two objects must produce the same integer result.
Object.equals(java.lang.Object)
method, then calling the hashCode method on each of the
two objects must produce distinct integer results. However, the
programmer should be aware that producing distinct integer results
for unequal objects may improve the performance of hash tables.
As much as is reasonably practical, the hashCode method defined by
class Object does return distinct integers for distinct
objects. (This is typically implemented by converting the internal
address of the object into an integer, but this implementation
technique is not required by the
Java™ programming language.)
hashCode in class ObjectObject.equals(java.lang.Object),
System.identityHashCode(java.lang.Object)public boolean equals(Object o)
java.lang.Object
The equals method implements an equivalence relation
on non-null object references:
x, x.equals(x) should return
true.
x and y, x.equals(y)
should return true if and only if
y.equals(x) returns true.
x, y, and z, if
x.equals(y) returns true and
y.equals(z) returns true, then
x.equals(z) should return true.
x and y, multiple invocations of
x.equals(y) consistently return true
or consistently return false, provided no
information used in equals comparisons on the
objects is modified.
x,
x.equals(null) should return false.
The equals method for class Object implements
the most discriminating possible equivalence relation on objects;
that is, for any non-null reference values x and
y, this method returns true if and only
if x and y refer to the same object
(x == y has the value true).
Note that it is generally necessary to override the hashCode
method whenever this method is overridden, so as to maintain the
general contract for the hashCode method, which states
that equal objects must have equal hash codes.
equals in class Objecto - the reference object with which to compare.true if this object is the same as the obj
argument; false otherwise.Object.hashCode(),
HashMappublic String toString()
java.lang.ObjecttoString method returns a string that
"textually represents" this object. The result should
be a concise but informative representation that is easy for a
person to read.
It is recommended that all subclasses override this method.
The toString method for class Object
returns a string consisting of the name of the class of which the
object is an instance, the at-sign character `@', and
the unsigned hexadecimal representation of the hash code of the
object. In other words, this method returns a string equal to the
value of:
getClass().getName() + '@' + Integer.toHexString(hashCode())