net.sf.saxon.s9api.streams

Class XdmCollectors

java.lang.Object

net.sf.saxon.s9api.streams.XdmCollectors

public class XdmCollectors
extends java.lang.Object

This class contains a number of static methods that deliver implementations of the Collector interface suitable for use with streams processing XDM nodes and other items.

For example, the method asNode can be used in an expression such as XdmNode n = x.select(child("author")).collect(asNode()) to indicate that the content of the stream delivered by the select() call is to be delivered as a single XdmNode object, and that an exception should occur if the result is anything other than a single node.

Although these methods can be used directly as arguments to Stream.collect(java.util.function.Supplier<R>, java.util.function.BiConsumer<R, ? super T>, java.util.function.BiConsumer<R, R>), it is usually more convenient to use them indirectly, the form of terminal operations on the class XdmStream, which extends Stream. So a more usual usage would be XdmNode n = x.select(child("author")).asNode()

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	XdmCollectors.MultipleItemException Unchecked exception that occurs when a collector method such as asAtomic() or asOptionalNode() is called, and the sequence contains more than one item.

Constructor Summary

Constructors

Constructor and Description
XdmCollectors()

Method Summary

Modifier and Type	Method and Description
static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<XdmAtomicValue,XdmAtomicValue>	asAtomic() This method provides a Collector that returns the content of a stream as a single atomic value, that is, an instance of XdmAtomicValue.
static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<java.util.List<XdmAtomicValue>,XdmAtomicValue>	asListOfAtomic() This method provides a Collector that returns the content of a stream as a list of atomic values (that is, as an instance of List<XdmAtomicValue>)
static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<java.util.List<XdmNode>,XdmNode>	asListOfNodes() This method provides a Collector that returns the content of a stream as a list of XdmNode objects (that is, as an instance of List<XdmNode>)
static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<XdmNode,XdmNode>	asNode() This method provides a Collector that returns the content of a stream as a single XdmNode.
static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<java.util.Optional<XdmAtomicValue>,XdmAtomicValue>	asOptionalAtomic() This method provides a Collector that returns the content of a stream as an optional atomic value (that is, as an instance of Optional<XdmAtomicValue>)
static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<java.util.Optional<XdmNode>,XdmNode>	asOptionalNode() This method provides a Collector that returns the content of a stream as an optional XdmNode (that is, as an instance of Optional<XdmNode>)
static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<java.util.Optional<java.lang.String>,XdmItem>	asOptionalString() This method provides a Collector that returns the content of a stream as an optional String (that is, as an instance of Optional<String>) The stream must deliver either nothing, or a single XdmItem; the collector returns the string value of that item.
static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<java.lang.String,XdmItem>	asString() This method provides a Collector that returns the content of a stream as an optional String (that is, as an instance of Optional<String>) The stream must deliver a single XdmItem; the collector returns the string value of that item.
static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<XdmValue,XdmItem>	asXdmValue() This method provides a Collector that returns the content of a stream as an XdmValue

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

XdmCollectors

public XdmCollectors()

Method Detail

asXdmValue

public static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<XdmValue,XdmItem> asXdmValue()

This method provides a Collector that returns the content of a stream as an XdmValue

Returns:

a collector that returns the single node delivered by the stream, or null if the stream is empty

Throws:

java.lang.ClassCastException - if the stream contains an item that is not a node

asNode

public static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<XdmNode,XdmNode> asNode()

This method provides a Collector that returns the content of a stream as a single XdmNode.

Returns:

a collector that returns the single node delivered by the stream

Throws:

java.util.NoSuchElementException - if the stream is empty

XdmCollectors.MultipleItemException - if the stream contains more than one node

java.lang.ClassCastException - if the stream contains an item that is not a node

asOptionalNode

public static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<java.util.Optional<XdmNode>,XdmNode> asOptionalNode()

This method provides a Collector that returns the content of a stream as an optional XdmNode (that is, as an instance of Optional<XdmNode>)

Returns:

a collector that returns the single node delivered by the stream, or Optional#empty() if the stream is empty

Throws:

XdmCollectors.MultipleItemException - if the stream contains more than one node

java.lang.ClassCastException - if the stream contains an item that is not a node

asListOfNodes

public static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<java.util.List<XdmNode>,XdmNode> asListOfNodes()

This method provides a Collector that returns the content of a stream as a list of XdmNode objects (that is, as an instance of List<XdmNode>)

Returns:

a collector that returns the single node delivered by the stream, or null if the stream is empty

Throws:

java.lang.ClassCastException - if the stream contains an item that is not a node

asListOfAtomic

public static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<java.util.List<XdmAtomicValue>,XdmAtomicValue> asListOfAtomic()

This method provides a Collector that returns the content of a stream as a list of atomic values (that is, as an instance of List<XdmAtomicValue>)

Returns:

a collector that returns the list of atomic values delivered by the stream

Throws:

java.lang.ClassCastException - if the stream contains an item that is not an atomic value

asOptionalAtomic

public static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<java.util.Optional<XdmAtomicValue>,XdmAtomicValue> asOptionalAtomic()

This method provides a Collector that returns the content of a stream as an optional atomic value (that is, as an instance of Optional<XdmAtomicValue>)

Returns:

a collector that returns the single atomic value delivered by the stream, or Optional.empty() if the stream is empty

Throws:

java.lang.ClassCastException - if the stream contains an item that is not a node

asAtomic

public static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<XdmAtomicValue,XdmAtomicValue> asAtomic()

This method provides a Collector that returns the content of a stream as a single atomic value, that is, an instance of XdmAtomicValue. The stream must deliver a single atomic value.

Returns:

a collector that returns the string value of the single item delivered by the stream

Throws:

java.util.NoSuchElementException - if the stream is empty

XdmCollectors.MultipleItemException - if the stream contains more than one item

java.lang.ClassCastException - if the stream delivers an item that is not an atomic value

asOptionalString

public static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<java.util.Optional<java.lang.String>,XdmItem> asOptionalString()

This method provides a Collector that returns the content of a stream as an optional String (that is, as an instance of Optional<String>) The stream must deliver either nothing, or a single XdmItem; the collector returns the string value of that item.

Returns:

a collector that returns the string value of the single item delivered by the stream, if any

Throws:

XdmCollectors.MultipleItemException - if the stream contains more than one item

java.lang.UnsupportedOperationException - if the stream contains an item with no string value (such as a function item or an element with element-only content)

asString

public static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<java.lang.String,XdmItem> asString()

This method provides a Collector that returns the content of a stream as an optional String (that is, as an instance of Optional<String>) The stream must deliver a single XdmItem; the collector returns the string value of that item.

Returns:

a collector that returns the string value of the single item delivered by the stream, if any

Throws:

XdmCollectors.MultipleItemException - if the stream contains more than one item

java.util.NoSuchElementException - if the stream is empty

java.lang.UnsupportedOperationException - if the stream contains an item with no string value (such as a function item or an element with element-only content)