RowSorter provides the basis for sorting and filtering. Beyond creating and installing a
RowSorter, you very rarely need to interact with one directly. Refer to {@link javax.swing.table.TableRowSorter TableRowSorter} for a concreteimplementation of
RowSorter for
JTable.
RowSorter's primary role is to provide a mapping between two coordinate systems: that of the view (for example a JTable) and that of the underlying data source, typically a model.
The view invokes the following methods on the RowSorter:
toggleSortOrder — The view invokes this when the appropriate user gesture has occurred to trigger a sort. For example, the user clicked a column header in a table. - One of the model change methods — The view invokes a model change method when the underlying model has changed. There may be order dependencies in how the events are delivered, so a
RowSorter should not update its mapping until one of these methods is invoked.
Because the view makes extensive use of the
convertRowIndexToModel,
convertRowIndexToView and
getViewRowCount methods, these methods need to be fast.
RowSorter provides notification of changes by way of RowSorterListener. Two types of notification are sent:
RowSorterEvent.Type.SORT_ORDER_CHANGED — notifies listeners that the sort order has changed. This is typically followed by a notification that the sort has changed. RowSorterEvent.Type.SORTED — notifies listeners that the mapping maintained by the RowSorter has changed in some way.
RowSorter implementations typically don't have a one-to-one mapping with the underlying model, but they can. For example, if a database does the sorting,
toggleSortOrder might call through to the database (on a background thread), and override the mapping methods to return the argument that is passed in.
Concrete implementations of RowSorter need to reference a model such as TableModel or ListModel. The view classes, such as JTable and JList, will also have a reference to the model. To avoid ordering dependencies, RowSorter implementations should not install a listener on the model. Instead the view class will call into the RowSorter when the model changes. For example, if a row is updated in a TableModel JTable invokes rowsUpdated. When the model changes, the view may call into any of the following methods: modelStructureChanged, allRowsChanged, rowsInserted, rowsDeleted and rowsUpdated.
@param < M> the type of the underlying model
@see javax.swing.table.TableRowSorter
@since 1.6