java.lang.Object
- com.vaadin.flow.data.provider.AbstractDataView<T>
- - com.vaadin.flow.data.provider.AbstractLazyDataView<T>

Type Parameters:

T - the type of data

All Implemented Interfaces:

DataView<T>, LazyDataView<T>, Serializable
```
public abstract class AbstractLazyDataView<T>
extends AbstractDataView<T>
implements LazyDataView<T>
```
Abstract lazy data view implementation which handles the interaction with a data communicator.

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	Description
`AbstractLazyDataView(DataCommunicator<T> dataCommunicator, Component component)`	Creates a new instance and verifies the passed data provider is compatible with this data view implementation.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`protected DataCommunicator<T>`	`getDataCommunicator()`	Returns the data communicator for the component and checks that the data provider is of the correct type.
`T`	`getItem(int index)`	Gets the item at the given index from the data available to the component.
`int`	`getItemCountEstimate()`	Gets the item count estimate.
`int`	`getItemCountEstimateIncrease()`	Gets the item count estimate increase - how much the item count estimate is increased once the previous item count estimate has been reached.
`Stream<T>`	`getItems()`	Get the full data available to the component.
`protected Class<?>`	`getSupportedDataProviderType()`	Returns supported `DataProvider` type for this `DataView`.
`void`	`setItemCountEstimate(int itemCountEstimate)`	Sets the estimated item count for the component.
`void`	`setItemCountEstimateIncrease(int itemCountEstimateIncrease)`	Sets how much the item count estimate is increased once the previous item count estimate has been reached.
`void`	`setItemCountFromDataProvider()`	Switches the component to get the exact item count from the data provider's `DataProvider.size(Query)`.
`void`	`setItemCountUnknown()`	Switches the component to automatically extend the number of items as the previous end is almost reached.

Methods inherited from class com.vaadin.flow.data.provider.AbstractDataView
addIdentifierProviderChangeListener, addItemCountChangeListener, equals, getIdentifierProvider, refreshAll, refreshItem, setIdentifierProvider, verifyDataProviderType

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.vaadin.flow.data.provider.DataView
addItemCountChangeListener, refreshAll, refreshItem, setIdentifierProvider

- Constructor Detail
  - AbstractLazyDataView
```
public AbstractLazyDataView(DataCommunicator<T> dataCommunicator,
                            Component component)
```
    Creates a new instance and verifies the passed data provider is compatible with this data view implementation.
    
    Parameters:
    
    dataCommunicator - the data communicator of the component
    
    component - the component
- Method Detail
  - getDataCommunicator
```
protected DataCommunicator<T> getDataCommunicator()
```
    Returns the data communicator for the component and checks that the data provider is of the correct type.
    
    Returns:
    
    the data communicator
  - getItem
```
public T getItem(int index)
```
    Gets the item at the given index from the data available to the component. Data is filtered and sorted the same way as in the component.
    Calling this method with an index that is not currently active in the component will cause a query to the backend, so do not call this method carelessly. Use UI.beforeClientResponse(Component, SerializableConsumer) to access items that will be fetched later on.
    
    Specified by:
    
    getItem in interface DataView<T>
    
    Parameters:
    
    index - the index of the item to get
    
    Returns:
    
    item on index
    
    Throws:
    
    IndexOutOfBoundsException - requested index is outside of the filtered and sorted data set
  - getItems
```
public Stream<T> getItems()
```
    Description copied from interface: DataView
    
    Get the full data available to the component. Data is filtered and sorted the same way as in the component.
    
    Specified by:
    
    getItems in interface DataView<T>
    
    Overrides:
    
    getItems in class AbstractDataView<T>
    
    Returns:
    
    filtered and sorted 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
  - setItemCountEstimate
```
public void setItemCountEstimate(int itemCountEstimate)
```
    Description copied from interface: LazyDataView
    
    Sets the estimated item count for the component. The component will automatically fetch more items once the estimate is reached or adjust the count if the backend runs out of items before the end. Use this when the backend will have a lot more items than shown by default and it should be shown to the user.
    The given estimate is discarded if it is less than the currently shown range or if the actual number of items has been determined. The estimate shouldn't be less than two pages (see setPageSize(int) in the component) or it causes unnecessary backend requests.
    
    Specified by:
    
    setItemCountEstimate in interface LazyDataView<T>
    
    Parameters:
    
    itemCountEstimate - estimated item count of the backend
    
    See Also:
    
    LazyDataView.setItemCountUnknown(), LazyDataView.setItemCountEstimateIncrease(int)
  - getItemCountEstimate
```
public int getItemCountEstimate()
```
    Description copied from interface: LazyDataView
    
    Gets the item count estimate. The default value depends on the component.
    
    Specified by:
    
    getItemCountEstimate in interface LazyDataView<T>
    
    Returns:
    
    item count estimate
    
    See Also:
    
    LazyDataView.setItemCountEstimate(int)
  - setItemCountEstimateIncrease
```
public void setItemCountEstimateIncrease(int itemCountEstimateIncrease)
```
    Description copied from interface: LazyDataView
    
    Sets how much the item count estimate is increased once the previous item count estimate has been reached. Use this when the user should be able to scroll down faster. The default value depends on the component.
    As an example, with an estimate of 1000 and an increase of 500, when scrolling down the item count will be: 1000, 1500, 2000, 2500... until the backend runs out of items.
    NOTE: the given increase should not be less than the setPageSize(int) set in the component, or there will be unnecessary backend requests.
    
    Specified by:
    
    setItemCountEstimateIncrease in interface LazyDataView<T>
    
    Parameters:
    
    itemCountEstimateIncrease - how much the item count estimate is increased
    
    See Also:
    
    LazyDataView.setItemCountEstimate(int)
  - getItemCountEstimateIncrease
```
public int getItemCountEstimateIncrease()
```
    Description copied from interface: LazyDataView
    
    Gets the item count estimate increase - how much the item count estimate is increased once the previous item count estimate has been reached. The default value depends on the component.
    
    Specified by:
    
    getItemCountEstimateIncrease in interface LazyDataView<T>
    
    Returns:
    
    the item count estimate increase
    
    See Also:
    
    LazyDataView.setItemCountEstimateIncrease(int)
  - setItemCountFromDataProvider
```
public void setItemCountFromDataProvider()
```
    Description copied from interface: LazyDataView
    
    Switches the component to get the exact item count from the data provider's DataProvider.size(Query). Use this when it is cheap to get the exact item count and it is desired that the user sees the "full scrollbar size".
    
    Specified by:
    
    setItemCountFromDataProvider in interface LazyDataView<T>
  - setItemCountUnknown
```
public void setItemCountUnknown()
```
    Description copied from interface: LazyDataView
    
    Switches the component to automatically extend the number of items as the previous end is almost reached. The component stops increasing the number of items once the backend has run out of items. Not getting the exact size of the backend upfront can improve performance with large sets of data.
    The default initial item count and how much the item count is increased depends on the component. These values can be customized with LazyDataView.setItemCountEstimate(int) and LazyDataView.setItemCountEstimateIncrease(int) when the backend has a lot of items and faster scrolling down is desired.
    
    Specified by:
    
    setItemCountUnknown in interface LazyDataView<T>

Class AbstractLazyDataView<T>

Field Summary

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

Constructor Summary

Method Summary

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

Methods inherited from class java.lang.Object

Methods inherited from interface com.vaadin.flow.data.provider.DataView

Constructor Detail

AbstractLazyDataView

Method Detail

getDataCommunicator

getItem

getItems

getSupportedDataProviderType

setItemCountEstimate

getItemCountEstimate

setItemCountEstimateIncrease

getItemCountEstimateIncrease

setItemCountFromDataProvider

setItemCountUnknown