org.eclipse.rdf4j.query.impl

Class EmptyBindingSet

java.lang.Object

org.eclipse.rdf4j.query.impl.EmptyBindingSet

All Implemented Interfaces:

Serializable, Iterable<Binding>, BindingSet

public class EmptyBindingSet
extends Object
implements BindingSet

An immutable empty BindingSet.

Author:

Arjohn Kampman

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
EmptyBindingSet()

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object o) Compares a BindingSet object to another object.
Binding	getBinding(String bindingName) Gets the binding with the specified name from this BindingSet.
Set<String>	getBindingNames() Gets the names of the bindings in this BindingSet.
static BindingSet	getInstance()
Value	getValue(String bindingName) Gets the value of the binding with the specified name from this BindingSet.
boolean	hasBinding(String bindingName) Checks whether this BindingSet has a binding with the specified name.
int	hashCode() The hash code of a binding is defined as the bit-wise XOR of the hash codes of its bindings:
Iterator<Binding>	iterator() Creates an iterator over the bindings in this BindingSet.
int	size() Returns the number of bindings in this BindingSet.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

EmptyBindingSet

public EmptyBindingSet()

Method Detail

getInstance

public static BindingSet getInstance()

iterator

public Iterator<Binding> iterator()

Description copied from interface: BindingSet

Creates an iterator over the bindings in this BindingSet. This only returns bindings with non-null values. An implementation is free to return the bindings in arbitrary order.

Specified by:

iterator in interface Iterable<Binding>

Specified by:

iterator in interface BindingSet

getBindingNames

public Set<String> getBindingNames()

Description copied from interface: BindingSet

Gets the names of the bindings in this BindingSet.

Specified by:

getBindingNames in interface BindingSet

Returns:

A set of binding names.

getBinding

public Binding getBinding(String bindingName)

Description copied from interface: BindingSet

Gets the binding with the specified name from this BindingSet.

Specified by:

getBinding in interface BindingSet

Parameters:

bindingName - The name of the binding.

Returns:

The binding with the specified name, or null if there is no such binding in this BindingSet.

hasBinding

public boolean hasBinding(String bindingName)

Description copied from interface: BindingSet

Checks whether this BindingSet has a binding with the specified name.

Specified by:

hasBinding in interface BindingSet

Parameters:

bindingName - The name of the binding.

Returns:

true if this BindingSet has a binding with the specified name, false otherwise.

getValue

public Value getValue(String bindingName)

Description copied from interface: BindingSet

Gets the value of the binding with the specified name from this BindingSet.

Specified by:

getValue in interface BindingSet

Parameters:

bindingName - The name of the binding.

Returns:

The value of the binding with the specified name, or null if there is no such binding in this BindingSet.

size

public int size()

Description copied from interface: BindingSet

Returns the number of bindings in this BindingSet.

Specified by:

size in interface BindingSet

Returns:

The number of bindings in this BindingSet.

equals

public boolean equals(Object o)

Description copied from interface: BindingSet

Compares a BindingSet object to another object.

Specified by:

equals in interface BindingSet

Overrides:

equals in class Object

Parameters:

o - The object to compare this binding to.

Returns:

true if the other object is an instance of BindingSet and it contains the same set of bindings (disregarding order), false otherwise.

hashCode

public int hashCode()

Description copied from interface: BindingSet

The hash code of a binding is defined as the bit-wise XOR of the hash codes of its bindings:

 int hashCode = 0;

 for (Binding binding : this) {
        hashCode ˆ= binding.getName().hashCode() ˆ binding.getValue().hashCode();
 }
 

Note: the calculated hash code intentionally does not depend on the order in which the bindings are iterated over.

Specified by:

hashCode in interface BindingSet

Overrides:

hashCode in class Object

Returns:

A hash code for the BindingSet.

toString

public String toString()

Overrides:

toString in class Object