XdmCollectors (saxon JavaDoc)

java.lang.Object
- net.sf.saxon.s9api.streams.XdmCollectors

```
public class XdmCollectors
extends 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()

Constructors
Constructor and Description
`XdmCollectors()`

Method Summary

All Methods Static Methods Concrete Methods
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<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<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<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<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<Optional<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<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:
    
    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:
    
    NoSuchElementException - if the stream is empty
    
    XdmCollectors.MultipleItemException - if the stream contains more than one node
    
    ClassCastException - if the stream contains an item that is not a node
  - asOptionalNode
```
public static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<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
    
    ClassCastException - if the stream contains an item that is not a node
  - asListOfNodes
```
public static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<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:
    
    ClassCastException - if the stream contains an item that is not a node
  - asListOfAtomic
```
public static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<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:
    
    ClassCastException - if the stream contains an item that is not an atomic value
  - asOptionalAtomic
```
public static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<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:
    
    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:
    
    NoSuchElementException - if the stream is empty
    
    XdmCollectors.MultipleItemException - if the stream contains more than one item
    
    ClassCastException - if the stream delivers an item that is not an atomic value
  - asOptionalString
```
public static net.sf.saxon.s9api.streams.XdmCollectors.XdmCollector<Optional<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
    
    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<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
    
    NoSuchElementException - if the stream is empty
    
    UnsupportedOperationException - if the stream contains an item with no string value (such as a function item or an element with element-only content)

Class XdmCollectors

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

XdmCollectors

Method Detail

asXdmValue

asNode

asOptionalNode

asListOfNodes

asListOfAtomic

asOptionalAtomic

asAtomic

asOptionalString

asString