GXT3 - ColumnSelectionAppearance ClassCastException

Question

I have trouble implementing the GridSelectionModel (using CheckBoxSelectionModel as an inspiration).
I'd like to create a RadioSelectionModel but I have a ClassCastException when I call my constructor. Here's my class structure (If needed I put some code but I don't think that's necessary). I'm using list and sublist to show the classes and embedded classes :

• class RadioSelectionModel < M > extends GridSelectionModel< M >
  • interface RadioColumnAppearance < M >
• class RadioColumnDefaultAppearance < M >
  • interface RadioColumnStyle extends CssResource, ColumnHeaderStyles, GridDataTableStyles
  • interface RadioColumnResources extends ClientBundle

The RadioColumnAppearance is link to RadioColumnDefaultAppearance by a gwt.xml file with :

<replace-with
    class="com.app.appearance.RadioColumnDefaultAppearance">
    <when-type-is
        class="com.app.grid.RadioSelectionModel.RadioColumnAppearance" />
</replace-with>

I happened to found that the ClassCastException is when I call GWT.create( RadioColumnAppearance.class ) but I don't know what is exactly the problem and how I can solve it

EDIT : Here's the RadioColumnDefaultAppearance code. I believe that the problem is in here because I only have the exception when I call GWT.create. About the error, it's a simple message I get in my browser console Uncaught java.lang.ClassCastException :

public class RadioColumnDefaultAppearance < M > implements CheckBoxColumnAppearance< M >
{

public interface RadioColumnStyle extends CheckBoxColumnStyle
{

}

public interface RadioColumnResources extends ClientBundle
{
    @Source( "/css/RadioColumn.css" )
    RadioColumnStyle style();

    @Source( "column.png" )
    @ImageOptions( repeatStyle = RepeatStyle.Vertical )
    ImageResource specialColumn();

    @Source( "column_checked.png" )
    @ImageOptions( repeatStyle = RepeatStyle.Vertical )
    ImageResource specialColumnSelected();
}

private final RadioColumnResources resources;
private final RadioColumnStyle style;

public RadioColumnDefaultAppearance()
{

    this( GWT.< RadioColumnResources > create( RadioColumnResources.class ) );
}

public RadioColumnDefaultAppearance( RadioColumnResources resources )
{
    this.resources = resources;

    this.style = this.resources.style();

    StyleInjectorHelper.ensureInjected( style, true );
}

public void renderRadio( Context context, M value, SafeHtmlBuilder sb )
{
    sb.appendHtmlConstant( "<div class='x-grid-row-checker'>&#160;</div>" );
}


}

Answer 1

Your RadioColumnDefaultAppearance does not implement the RadioColumnAppearance interface. If you want to define a default implementation for an interface, the class must implements that interface otherwise it would not possible to assign an instance of the implementation class to an interface reference.