Package com.vaadin.client.flow.nodefeature

Class NodeList

java.lang.Object

com.vaadin.client.flow.nodefeature.NodeFeature

com.vaadin.client.flow.nodefeature.NodeList

All Implemented Interfaces:

ReactiveValue

public class NodeList
extends NodeFeature
implements ReactiveValue

A state node feature that structures data as a list.

The list works as a reactive value with regards to its structure. A Computation will get a dependency on this list for any read operation that depends on the list structure, such as querying the length, iterating the list or finding the index of an item. Accessing an item by index does not create a dependency. The Computation is invalidated when items are added, removed, reordered or replaced. It is not invalidated when the contents of an item is updated since all items are expected to be either immutable or reactive values of their own.

Since:

1.0

Author:

Vaadin Ltd

Constructor Summary

Constructors

Constructor	Description
NodeList(int id, StateNode node)	Creates a new list.

Method Summary

Modifier and Type	Method	Description
void	add(int index, Object item)	Shorthand for adding the given item at the given index.
elemental.events.EventRemover	addReactiveValueChangeListener(ReactiveValueChangeListener reactiveValueChangeListener)	Adds a listener that has a dependency to this value, and should be notified when this value changes.
elemental.events.EventRemover	addSpliceListener(ListSpliceListener listener)	Adds a listener that will be notified when the list structure changes.
void	clear()	Removes all the nodes from the list.
elemental.json.JsonValue	convert(Function<Object,elemental.json.JsonValue> converter)	Convert the feature values into a JsonValue using provided converter for the values stored in the feature (i.e.
void	forEach(JsCollections.ForEachCallback<Object> callback)	Iterates all values in this list.
Object	get(int index)	Gets the item at the given index.
elemental.json.JsonValue	getDebugJson()	Gets a JSON object representing the contents of this feature.
boolean	hasBeenCleared()	Returns true if the list instance has been cleared at some point.
int	length()	Gets the number of items in this list.
void	set(int index, Object value)	Sets the value at the given index.
void	splice(int index, int remove)	Removes a number of items at the given index.
void	splice(int index, int remove, JsArray<?> add)	Removes and adds a number of items at the given index.

Methods inherited from class com.vaadin.client.flow.nodefeature.NodeFeature

getAsDebugJson, getId, getNode

Methods inherited from class java.lang.Object

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

Constructor Detail

NodeList

public NodeList(int id,
                StateNode node)

Creates a new list.

Parameters:

id - the id of the list

node - the node of the list

Method Detail

length

public int length()

Gets the number of items in this list.

Returns:

the number of items

get

public Object get(int index)

Gets the item at the given index.

Parameters:

index - the index

Returns:

the item at the index

set

public void set(int index,
                Object value)

Sets the value at the given index.

Parameters:

index - the index

value - the value to set

add

public void add(int index,
                Object item)

Shorthand for adding the given item at the given index. This method delegates to splice(int, int, JsArray) which updates the list contents and fires the appropriate event.

Parameters:

index - the index where the item should be added

item - the new item to add

splice

public void splice(int index,
                   int remove)

Removes a number of items at the given index. This causes a ListSpliceEvent to be fired.

Parameters:

index - the index at which do do the operation

remove - the number of items to remove

clear

public void clear()

Removes all the nodes from the list. This causes a ListSpliceEvent to be fired, with ListSpliceEvent.isClear() as true.

splice

public final void splice(int index,
                         int remove,
                         JsArray<?> add)

Removes and adds a number of items at the given index.

This causes a ListSpliceEvent to be fired.

Parameters:

index - the index at which do do the operation

remove - the number of items to remove

add - an array of new items to add

getDebugJson

public elemental.json.JsonValue getDebugJson()

Description copied from class: NodeFeature

Gets a JSON object representing the contents of this feature. Only intended for debugging purposes.

Specified by:

getDebugJson in class NodeFeature

Returns:

a JSON representation

convert

public elemental.json.JsonValue convert(Function<Object,elemental.json.JsonValue> converter)

Description copied from class: NodeFeature

Convert the feature values into a JsonValue using provided converter for the values stored in the feature (i.e. primitive types, StateNodes).

Specified by:

convert in class NodeFeature

Parameters:

converter - converter to convert values stored in the feature

Returns:

resulting converted value

addSpliceListener

public elemental.events.EventRemover addSpliceListener(ListSpliceListener listener)

Adds a listener that will be notified when the list structure changes.

Parameters:

listener - the list change listener

Returns:

an event remover that can be used for removing the added listener

addReactiveValueChangeListener

public elemental.events.EventRemover addReactiveValueChangeListener(ReactiveValueChangeListener reactiveValueChangeListener)

Description copied from interface: ReactiveValue

Adds a listener that has a dependency to this value, and should be notified when this value changes.

Specified by:

addReactiveValueChangeListener in interface ReactiveValue

Parameters:

reactiveValueChangeListener - the listener to add

Returns:

an event remover that can be used for removing the added listener

forEach

public void forEach(JsCollections.ForEachCallback<Object> callback)

Iterates all values in this list.

Parameters:

callback - the callback to invoke for each value

hasBeenCleared

public boolean hasBeenCleared()

Returns true if the list instance has been cleared at some point.

Returns:

true if the list instance has been cleared