如何使用Nebula Nattable的PreserveselectionModel？

Question

• 我希望选择整行。我可以使用RowonlySelectionConfiguration和RowonlySelectionBindings.
实现这一点
• 如果我选择了一行，我希望该选择保持在那里，当该行中的某些数据得到更新时，不要清除该选择。我该怎么做？
• 如果选择了一行，并且该行中元素的位置发生了变化（例如，删除了前面的一个元素，并且位置变为索引-1)，我希望选择用该元素改变位置，以便在改变后选择相同的元素。我该怎么做？

我看到文档中谈到了可用于此目的的preserveselectionmodel:

如果在以前的版本中使用PreservesElectionStructuralChangeEventHandler解决方案来不清除结构更改上的选择，您将注意到此解决方案不再起作用。如果您仍然需要这种行为，现在可以通过配置和设置SelectionModel实例来实现同样的功能，如下所示：

SelectionModel model = new SelectionModel(selectionLayer); 
// configure to not clear the selection on structural changes 
model.setClearSelectionOnChange(false); 
selectionLayer.setSelectionModel(model);

所以我想我必须使用preserveselectionmodel？但是在那里我不能调用setClearSelectiononChange(false)。默认情况下它会这样做吗？

如何使用preserveselectionmodel？我在构造函数中传递什么？

我在一个名为TableBodyLayerStack的类中实现了自己的BodyLayerStack，我在构造函数中尝试了这一点：

public TableBodyLayerStack(IUniqueIndexLayer underlyingLayer) {
    super(underlyingLayer);
    columnReorderLayer = new ColumnReorderLayer(underlyingLayer);
    columnHideShowLayer = new ColumnHideShowLayer(columnReorderLayer);
    selectionLayer = new SelectionLayer(columnHideShowLayer, null, true, false);
    PreserveSelectionModel<?> selectionModel = new PreserveSelectionModel<>(
            selectionLayer, null, null);
    selectionLayer.setSelectionModel(selectionModel);
    selectionLayer.registerEventHandler(new SelectEventHandler(selectionLayer));
    viewportLayer = new ViewportLayer(selectionLayer);
    setUnderlyingLayer(viewportLayer);
    registerCommandHandler(new CopyDataCommandHandler(selectionLayer));
}

// ...

bodyLayer = new TableBodyLayerStack(eventLayer);
// register different selection move command handler that always moves by row
bodyLayer.getSelectionLayer().addConfiguration(new RowOnlySelectionConfiguration<T>());

// register selection bindings that will perform row selections instead of cell selections
// registering the bindings on a layer that is above the SelectionLayer will consume the
// commands before they are handled by the SelectionLayer
bodyLayer.addConfiguration(new RowOnlySelectionBindings());

// ...

Error while painting table: null
java.lang.NullPointerException
at org.eclipse.nebula.widgets.nattable.selection.preserve.PreserveSelectionModel.getRowPositionByRowObject(PreserveSelectionModel.java:520)
at org.eclipse.nebula.widgets.nattable.selection.preserve.PreserveSelectionModel.createMarkerPoint(PreserveSelectionModel.java:559)
at org.eclipse.nebula.widgets.nattable.selection.preserve.PreserveSelectionModel.getSelectionAnchor(PreserveSelectionModel.java:531)
at org.eclipse.nebula.widgets.nattable.selection.SelectionLayer.getSelectionAnchor(SelectionLayer.java:276)
at org.eclipse.nebula.widgets.nattable.selection.SelectionLayer.getConfigLabelsByPosition(SelectionLayer.java:415)
at org.eclipse.nebula.widgets.nattable.layer.AbstractLayerTransform.getConfigLabelsByPosition(AbstractLayerTransform.java:316)
at org.eclipse.nebula.widgets.nattable.layer.AbstractIndexLayerTransform.getConfigLabelsByPosition(AbstractIndexLayerTransform.java:318)
at org.eclipse.nebula.widgets.nattable.layer.CompositeLayer.getConfigLabelsByPosition(CompositeLayer.java:553)
at org.eclipse.nebula.widgets.nattable.layer.cell.AbstractLayerCell.getConfigLabels(AbstractLayerCell.java:48)
at org.eclipse.nebula.widgets.nattable.layer.AbstractLayer.getCellPainter(AbstractLayer.java:354)
at org.eclipse.nebula.widgets.nattable.layer.AbstractLayerTransform.getCellPainter(AbstractLayerTransform.java:336)
at org.eclipse.nebula.widgets.nattable.layer.AbstractLayerTransform.getCellPainter(AbstractLayerTransform.java:336)
at org.eclipse.nebula.widgets.nattable.layer.AbstractLayerTransform.getCellPainter(AbstractLayerTransform.java:336)
at org.eclipse.nebula.widgets.nattable.layer.AbstractIndexLayerTransform.getCellPainter(AbstractIndexLayerTransform.java:340)
at org.eclipse.nebula.widgets.nattable.layer.AbstractLayerTransform.getCellPainter(AbstractLayerTransform.java:336)
at org.eclipse.nebula.widgets.nattable.layer.AbstractIndexLayerTransform.getCellPainter(AbstractIndexLayerTransform.java:340)
at org.eclipse.nebula.widgets.nattable.layer.CompositeLayer.getCellPainter(CompositeLayer.java:586)
at org.eclipse.nebula.widgets.nattable.painter.layer.CellLayerPainter.paintCell(CellLayerPainter.java:171)
at org.eclipse.nebula.widgets.nattable.painter.layer.CellLayerPainter.paintLayer(CellLayerPainter.java:81)
at org.eclipse.nebula.widgets.nattable.painter.layer.GridLineCellLayerPainter.paintLayer(GridLineCellLayerPainter.java:106)
at org.eclipse.nebula.widgets.nattable.selection.SelectionLayerPainter.paintLayer(SelectionLayerPainter.java:95)
at org.eclipse.nebula.widgets.nattable.layer.CompositeLayer$CompositeLayerPainter.paintLayer(CompositeLayer.java:913)
at org.eclipse.nebula.widgets.nattable.painter.layer.NatLayerPainter.paintLayer(NatLayerPainter.java:43)
at org.eclipse.nebula.widgets.nattable.NatTable.paintNatTable(NatTable.java:408)
at org.eclipse.nebula.widgets.nattable.NatTable.paintControl(NatTable.java:403)
...

任何帮助都很感激。

Answer 1

你走错了实现目标的轨道。首先，我将回答你们的问题：

>

所以我想我得用preserveselectionmodel？

但这给了我PreservesElectionModel中的NullPointerExceptions。我想这是因为我在PreservesElectionModel的构造函数中传递了空值。

我必须传递什么作为构造函数的参数？我从哪里获得这些值？

所以你需要做的事情是这样的：

selectionLayer.setSelectionModel(new RowSelectionModel<Person>(
        selectionLayer, bodyDataProvider, new IRowIdAccessor<Person>() {

        @Override
        public Serializable getRowId(Person rowObject) {
            return rowObject.getId();
        }

    }));

但是，如果要保持TableBodyLayerStack，您当然需要向TableBodyLayerStack提供IDataProvider和IrowidAccessor。

还要注意，您不必自己调用SelectionLayer#RegisterEventHandler（）！这是通过调用selectionLayer#setSelectionModel（）在内部完成的。

您可以在NatTable examples应用程序https://www.eclipse.org/NatTable/（右侧的Try It！按钮）中找到几个示例。对于您的问题，教程示例->Layers->Selection->RowSelectionExample似乎是一个值得关注的问题。