Package org.eclipse.nebula.widgets.nattable.extension.glazedlists.groupBy

Class GroupByComparator<T>

java.lang.Object

org.eclipse.nebula.widgets.nattable.extension.glazedlists.groupBy.GroupByComparator<T>

Type Parameters:

T - The type of the base objects carried in the TreeList

All Implemented Interfaces:

Comparator<Object>, IGroupByComparator<T>

public class GroupByComparator<T>
extends Object
implements IGroupByComparator<T>

Comparator that is used to sort the TreeList based on the groupBy information. Necessary for building the tree structure correctly.

See Also:

GroupByTreeFormat

Field Summary

Fields

Modifier and Type	Field	Description
protected IColumnAccessor<T>	columnAccessor
protected GroupByModel	groupByModel
protected Map<GroupByObject,org.eclipse.nebula.widgets.nattable.extension.glazedlists.groupBy.GroupByComparator.GroupByObjectValueCache>	groupByObjectComparatorCache	Cache that is used to increase the performance on sorting by summary values.
protected ISortModel	sortModel
protected Map<Integer,Boolean>	summaryColumnCache	Cache that is used to increase the performance on sorting.
protected IUniqueIndexLayer	treeLayer

Constructor Summary

Constructors

Constructor	Description
GroupByComparator(GroupByModel groupByModel, IColumnAccessor<T> columnAccessor)
GroupByComparator(GroupByModel groupByModel, IColumnAccessor<T> columnAccessor, GroupByDataLayer<T> dataLayer)

Method Summary

Modifier and Type	Method	Description
void	clearCache()	For performance reasons the IGroupByComparator might cache several information e.g.
int	compare(Object o1, Object o2)
protected Comparator	getComparator(int columnIndex)
ISortModel	getSortModel()
protected Object	getSummaryValueFromCache(GroupByObject groupBy, int columnIndex)	Returns the cached summary value for the given GroupByObject and column index.
protected Boolean	isSummaryColumn(GroupByObject groupBy, int columnIndex)
protected boolean	isTreeColumn(int columnIndex)
void	setDataLayer(GroupByDataLayer<T> dataLayer)
void	setSortModel(ISortModel sortModel)
void	setTreeLayer(IUniqueIndexLayer treeLayer)

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals, reversed, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Field Detail

groupByModel

protected final GroupByModel groupByModel

columnAccessor

protected final IColumnAccessor<T> columnAccessor

sortModel

protected ISortModel sortModel

treeLayer

protected IUniqueIndexLayer treeLayer

summaryColumnCache

protected Map<Integer,Boolean> summaryColumnCache

Cache that is used to increase the performance on sorting. The information whether a column is a summary column is only retrieved once and not calculated everytime.

groupByObjectComparatorCache

protected Map<GroupByObject,org.eclipse.nebula.widgets.nattable.extension.glazedlists.groupBy.GroupByComparator.GroupByObjectValueCache> groupByObjectComparatorCache

Cache that is used to increase the performance on sorting by summary values. Necessary because the summary value is not carried by the GroupByObject but retrieved from the GroupByDataLayer. Since the retrieval is done via row index rather than the GroupByObject, the row index needs to be calculated in order to get the correct values. This is done via List.indexOf(Object) which is quite time consuming. So this cache is used to reduce the amount of indexOf calls drastically.

As this cache is only used to increase the performance on sorting, the life time of this cache is reduced to a sort operation. It therefore gets cleared on every structural change.

Constructor Detail

GroupByComparator

public GroupByComparator(GroupByModel groupByModel,
                         IColumnAccessor<T> columnAccessor)

Parameters:

groupByModel - The GroupByModel necessary to retrieve information about the current groupBy state.

columnAccessor - The IColumnAccessor necessary to retrieve the column values of elements.

GroupByComparator

public GroupByComparator(GroupByModel groupByModel,
                         IColumnAccessor<T> columnAccessor,
                         GroupByDataLayer<T> dataLayer)

Parameters:

groupByModel - The GroupByModel necessary to retrieve information about the current groupBy state.

columnAccessor - The IColumnAccessor necessary to retrieve the column values of elements.

dataLayer - The GroupByDataLayer that should be used to retrieve groupBy summary values for sorting the tree structure. Can be null to avoid retrieving and inspecting summary values on sorting.

Method Detail

compare

public int compare(Object o1,
                   Object o2)

Specified by:

compare in interface Comparator<T>

isTreeColumn

protected boolean isTreeColumn(int columnIndex)

Parameters:

columnIndex - The column index of the column that should be checked.

Returns:

true if the column at the given index is the tree column, false if not or if no treeLayer reference is set to this GroupByComparator

getComparator

protected Comparator getComparator(int columnIndex)

Parameters:

columnIndex - The column index of the column for which the Comparator is requested.

Returns:

The Comparator that should be used to compare the values for elements in the given column. Returns the DefaultComparator in case there is no ISortModel configured for this GroupByComparator or no Comparator found for the given column.

getSortModel

public ISortModel getSortModel()

Specified by:

getSortModel in interface IGroupByComparator<T>

Returns:

The ISortModel that is used to retrieve the column value comparators and the sort direction in case a groupBy value is sorted which will directly affect the tree structure build. Can be null which leads to a static tree structure that only allows sorting for leafs within groups.

setSortModel

public void setSortModel(ISortModel sortModel)

Specified by:

setSortModel in interface IGroupByComparator<T>

Parameters:

sortModel - The ISortModel that is used to retrieve the column value comparators and the sort direction in case a groupBy value is sorted which will directly affect the tree structure build. Can be null which leads to a static tree structure that only allows sorting for leafs within groups.

setTreeLayer

public void setTreeLayer(IUniqueIndexLayer treeLayer)

Specified by:

setTreeLayer in interface IGroupByComparator<T>

Parameters:

treeLayer - The IUniqueIndexLayer that should be used to retrieve config labels for a column. Needed to be able to determine if the column which is used for sorting is the tree column. Can be null which avoids specialized handling of tree / non tree columns.

setDataLayer

public void setDataLayer(GroupByDataLayer<T> dataLayer)

Specified by:

setDataLayer in interface IGroupByComparator<T>

Parameters:

dataLayer - The GroupByDataLayer that should be used to retrieve groupBy summary values for sorting the tree structure. Can be null to avoid retrieving and inspecting summary values on sorting.

clearCache

public void clearCache()

Description copied from interface: IGroupByComparator

For performance reasons the IGroupByComparator might cache several information e.g. retrieved via GroupByDataLayer. This method is intended to clear those cached informations to avoid memory leaks or sorting based on old information.

Specified by:

clearCache in interface IGroupByComparator<T>

isSummaryColumn

protected Boolean isSummaryColumn(GroupByObject groupBy,
                                  int columnIndex)

Parameters:

groupBy - The GroupByObject for which the cache information is requested. Needed to retrieve the information if it is not yet cached.

columnIndex - The column for which the cache information is requested.

Returns:

true if the given column is a summary column, false if not

getSummaryValueFromCache

protected Object getSummaryValueFromCache(GroupByObject groupBy,
                                          int columnIndex)

Returns the cached summary value for the given GroupByObject and column index. If there is no cache information yet, it will be build.

Parameters:

groupBy - The GroupByObject for which the cache information is requested.

columnIndex - The column for which the cache information is requested.

Returns:

The summary value for the given GroupByObject and column index or null in case there is no GroupByDataLayer configured in for this GroupByComparator.