Here we describe how to implement a custom renderer for a listbox (org.zkoss.zul.ListitemRenderer). For the concepts about component, model and renderer, please refer to the Model-driven Display section.

When a listbox (org.zkoss.zul.Listbox) is assigned with a model, a default renderer is assigned too. The default renderer will assume that each list item has only one column, and it converts the data into a string directly¹. If you want to display multiple columns or retrieve a particular field of the data, you have to implement org.zkoss.zul.ListitemRenderer to handle the rendering.

For example,

public class MyRenderer implements ListitemRenderer{
    public void render(Listitem listitem, Object data, int index) {
        Listcell cell = new Listcell();
        listitem.appendChild(cell);
        if (data instanceof String[]){
            cell.appendChild(new Label(((String[])data)[0].toString()));
        } else if (data instanceof String){
            cell.appendChild(new Label(data.toString()));
        } else {
            cell.appendChild(new Label("UNKNOW:"+data.toString()));
        }
    }
}

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Version History

Version	Date	Content
6.0.0	February 2012	The index argument was introduced.

1. If the listbox is assigned a template called model, then the template will be used to render the listbox. For more information, please refer to the Listbox Template section. ↩