com.vaadin.flow.component.combobox.dataview

Class ComboBoxDataView<T>

java.lang.Object

com.vaadin.flow.data.provider.AbstractDataView<T>

com.vaadin.flow.component.combobox.dataview.ComboBoxDataView<T>

Type Parameters:

T - the item type

All Implemented Interfaces:

DataView<T>, Serializable

public class ComboBoxDataView<T>
extends AbstractDataView<T>

Implementation of generic data view for ComboBox. This implementation does not depend on a certain type of data provider, i.e. whether is it of in-memory or backend type. It can be used if the type of data provider is not either ListDataProvider or BackEndDataProvider.

Since:

See Also:

Serialized Form

Field Summary

Fields inherited from class com.vaadin.flow.data.provider.AbstractDataView

component, dataProviderSupplier, NULL_IDENTIFIER_ERROR_MESSAGE, NULL_ITEM_ERROR_MESSAGE

Constructor Summary

Constructors

Constructor and Description
ComboBoxDataView(DataCommunicator<T> dataCommunicator, ComboBox<T> comboBox) Creates a new generic data view for ComboBox and verifies the passed data provider is compatible with this data view implementation.

Method Summary

Modifier and Type	Method and Description
Registration	addItemCountChangeListener(ComponentEventListener<ItemCountChangeEvent<?>> listener) Add an item count change listener that is fired when the item count changes.
T	getItem(int index) Gets the item at the given index from the data available in the ComboBox's server-side.
Stream<T>	getItems() Gets the items available on the ComboBox's server-side.
protected Class<?>	getSupportedDataProviderType() Returns supported DataProvider type for this DataView.
void	setIdentifierProvider(IdentifierProvider<T> identifierProvider) Sets an identifier provider, which returns an identifier for the given item.

Methods inherited from class com.vaadin.flow.data.provider.AbstractDataView

equals, getIdentifierProvider, refreshAll, refreshItem, verifyDataProviderType

Methods inherited from class java.lang.Object

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

Constructor Detail

ComboBoxDataView

public ComboBoxDataView(DataCommunicator<T> dataCommunicator,
                        ComboBox<T> comboBox)

Creates a new generic data view for ComboBox and verifies the passed data provider is compatible with this data view implementation.

Parameters:

dataCommunicator - the data communicator of the component

comboBox - the ComboBox

Method Detail

getItem

public T getItem(int index)

Gets the item at the given index from the data available in the ComboBox's server-side.

This method does not take into account the ComboBox client-side filtering, since it doesn't change the item count on the server-side, but only makes it easier for users to search through the items in the UI.

Parameters:

index - item index number

Returns:

item on index

Throws:

IndexOutOfBoundsException - requested index is outside of the data set

getSupportedDataProviderType

protected Class<?> getSupportedDataProviderType()

Description copied from class: AbstractDataView

Returns supported DataProvider type for this DataView.

Specified by:

getSupportedDataProviderType in class AbstractDataView<T>

Returns:

supported data provider type

getItems

public Stream<T> getItems()

Gets the items available on the ComboBox's server-side.

This method does not take into account the ComboBox client-side filtering, since it doesn't change the item count on the server-side, but only makes it easier for users to search through the items in the UI.

Specified by:

getItems in interface DataView<T>

Overrides:

getItems in class AbstractDataView<T>

Returns:

items available on the server-side

setIdentifierProvider

public void setIdentifierProvider(IdentifierProvider<T> identifierProvider)

Description copied from interface: DataView

Sets an identifier provider, which returns an identifier for the given item. The identifier is used for comparing the equality of items. Usage example: dataView.setIdentifiedProvider(Item::getId);.

Specified by:

setIdentifierProvider in interface DataView<T>

Overrides:

setIdentifierProvider in class AbstractDataView<T>

Parameters:

identifierProvider - function that returns the non-null identifier for a given item

addItemCountChangeListener

public Registration addItemCountChangeListener(ComponentEventListener<ItemCountChangeEvent<?>> listener)

Add an item count change listener that is fired when the item count changes. This can happen for instance when filtering the items.

Item count change listener is bound to the component and will be retained even if the data changes by setting of a new items or DataProvider to component.

NOTE: when the component supports lazy loading (implements HasLazyDataView) and a count callback has not been provided, an estimate of the item count is used and increased until the actual count has been reached. When the estimate is used, the event is fired with the ItemCountChangeEvent.isItemCountEstimated() returning true.

Combo box fires ItemCountChangeEvent and notifies all the listeners added by this method, if the items count changed, for instance, due to adding or removing an item(s).

ComboBox's client-side filter change won't fire ItemCountChangeEvent, since it doesn't change the item count on the server-side, but only makes it easier for users to search through the items in the UI.

Specified by:

addItemCountChangeListener in interface DataView<T>

Overrides:

addItemCountChangeListener in class AbstractDataView<T>

Parameters:

listener - item count change listener to register

Returns:

registration for removing the listener