com.whitestein.lsps.vaadin.ui.components.table.dataset

Interface GroupingDataset.Reduction

All Superinterfaces:

Serializable

Enclosing class:

GroupingDataset

public static interface GroupingDataset.Reduction
extends Serializable

Reduction function to be performed over grouped items.

Method Summary

Modifier and Type	Method and Description
boolean	isReduceDefined(String columnId) Checks whether reduce is supported for given column.
Comparable<?>	reduce(String columnId, List<Object> records) Performs a reduction operation on given list of objects (sum, avg, etc) for given column ID and returns the result.

Method Detail

reduce

Comparable<?> reduce(String columnId,
                     List<Object> records)

Performs a reduction operation on given list of objects (sum, avg, etc) for given column ID and returns the result.

If the reduce is not supported or defined for given column, return null.

Parameters:

columnId - UITableColumn.getColumnId(), not null.

records - a list of records, never null, may be empty.

Returns:

the result of the reduction operation, may be null.

isReduceDefined

boolean isReduceDefined(String columnId)

Checks whether reduce is supported for given column. If not, reduce(java.lang.String, java.util.List) is not called for given column.

Parameters:

columnId - the column id, not null

Returns:

true if reduce function is defined for given column, false if not.