Replace widget

gistfile1.java

/**
 * Panel that wraps a GWT simple panel to be replaced by the widgetToAttach. This will make sure that the DIV element
 * is being replaced rather than having the widget inserted in it.
 * <p/>
 * The result of this will be to have a better, cleaner, dom.
 */
public class ReplacePanel implements IsWidget, HasOneWidget {
    static class WrongParentTypeException extends RuntimeException {
        public WrongParentTypeException(String message) {
            super(message);
        }
    }

    private IsWidget widget;

    public ReplacePanel() {
        widget = new SimplePanel();
    }

    @Override
    public Widget asWidget() {
        return widget.asWidget();
    }

    @Override
    public Widget getWidget() {
        return widget.asWidget();
    }

    @Override
    public void setWidget(Widget widgetToAttach) {
        Widget parentAsWidget = widget.asWidget().getParent();
        if (!(parentAsWidget instanceof HTMLPanel)) {
            throw new WrongParentTypeException("The parent of ReplacePanel must be of type HTMLPanel");
        }

        HTMLPanel parent = (HTMLPanel) parentAsWidget;

        parent.addAndReplaceElement(widgetToAttach, widget.asWidget().getElement());

        widget = widgetToAttach;
    }

    @Override
    public void setWidget(IsWidget widget) {
        setWidget(widget.asWidget());
    }
}

Just throw the exception inside the setWidget() method

and you don't detach logically the old widget

Yes, that is done through the addAndReplace of the parent html panel

you right !

LGTM !