GWT使用小部件和事件

Question

I m working with GWT 2.4 on an new application. I made a docklayoutpanel and I inserted a celllist on the west section of it. I need to create an event, every time a user clicks on an element of celllist on the west side of page a specific widget will load at the content of the docklayoutpanel.

Any suggestions?

Thank you

Answer 1

The following example should be self explanatory

// Create a cell to render each value.
TextCell textCell = new TextCell();

// Create a CellList that uses the cell.
CellList<String> cellList = new CellList<String>(textCell);
cellList.setKeyboardSelectionPolicy(KeyboardSelectionPolicy.ENABLED);

// Add a selection model to handle user selection.
final SingleSelectionModel<String> selectionModel = new SingleSelectionModel<String>();
cellList.setSelectionModel(selectionModel);
selectionModel.addSelectionChangeHandler(new SelectionChangeEvent.Handler() {
  public void onSelectionChange(SelectionChangeEvent event) {
    String selected = selectionModel.getSelectedObject();
    if (selected != null) {
      Window.alert("You selected: " + selected);
    }
  }
});

Instead of Window.alert("You selected: " + selected); you will need to change the widget shown on the eastern side of your panel.

This can be done in several ways, one of which is to expose the Dockpanel to the Selection Change Event either by declaring the Panel as a field to the class (not a local Variable in the constructor of the class) or as a final local variable in the constructor.

Another way is to do this by event handling. The eventBus methodology on the MVP design pattern is the proper way to do all thesee here for more information.