Method Details

• setItemCountCallback

  public void setItemCountCallback(CallbackDataProvider.CountCallback<T,Void> callback)

  Sets a callback that the Grid uses to get the exact item count in the backend. Use this when it is cheap to get the exact item count and it is desired that the user sees the "full scrollbar size".

  The given callback will be queried for the count instead of the data provider DataProvider.size(Query) method when the component has a distinct data provider set with HasLazyDataView.setItems(BackEndDataProvider).

  Parameters:

  callback - the callback to use for determining item count in the backend, not null

  See Also:

  • setItemCountFromDataProvider()
  • setItemCountUnknown()

• setItemCountFromDataProvider

  public void setItemCountFromDataProvider()

  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".

  Calling this method will clear any previously set count callback with the setItemCountCallback(CallbackDataProvider.CountCallback) method.

  Specified by:

  setItemCountFromDataProvider in interface LazyDataView<T>

  Overrides:

  setItemCountFromDataProvider in class AbstractLazyDataView<T>

• setItemCountEstimate

  public void setItemCountEstimate(int itemCountEstimate)

  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.

  Calling this method will clear any previously set count callback setItemCountCallback(CallbackDataProvider.CountCallback).

  Specified by:

  setItemCountEstimate in interface LazyDataView<T>

  Overrides:

  setItemCountEstimate in class AbstractLazyDataView<T>

  Parameters:

  itemCountEstimate - estimated item count of the backend

  See Also:

  • LazyDataView.setItemCountUnknown()
  • LazyDataView.setItemCountEstimateIncrease(int)

• setItemCountUnknown

  public void setItemCountUnknown()

  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.

  Calling this method will clear any previously set count callback setItemCountCallback(CallbackDataProvider.CountCallback).

  Specified by:

  setItemCountUnknown in interface LazyDataView<T>

  Overrides:

  setItemCountUnknown in class AbstractLazyDataView<T>