Question

If I have 2 .zul, one has a listbox, and another is the modal window. can they use the same controller? I just can’t get it work.

the question basically resume at, do I have to use apply="myController" in both .zul?
if I do that, I get nullpointerException at myList, because I think zk is instantiating 2 controller objects, and the modal doesn’t exist myList. but If I don’t apply the controller at modal.zul, nothing happens when I press buttons.

how can I make 2 .zul use same instance of controller?

mail.zul

<?variable-resolver class="org.zkoss.zkplus.spring.DelegatingVariableResolver"?>
<?init class="org.zkoss.zkplus.databind.AnnotateDataBinderInit" ?>
<zk>
    <hlayout>
    <div id="winDiv" apply="com.company.controller.ProductController">
        <vbox>
            <listbox id="myList" width="690px" height="300px" >
                <listhead>
                    <listheader hflex="min" label="id" sort="auto(id)" />
                    <listheader hflex="2" label="name" sort="auto(name)" />
                    <listheader hflex="4" label="description" sort="auto(description)" />
                                        <listheader hflex="min" label="opcion"/>
                                </listhead>
            </listbox>
        </vbox>
    </div>
            <button label="new" id="new"/>
        </hlayout>
</zk>

the modal.zul

<?xml version="1.0" encoding="UTF-8"?>
<?variable-resolver class="org.zkoss.zkplus.spring.DelegatingVariableResolver"?>
<window id="modalProductType" title="Nuevo tipo de producto" border="normal" width="420px"
    closable="true" position="center,center" **apply="com.company.controller.ProductController"**>

    <grid>
        <columns>
                <column hflex="1"/>
                <column hflex="2"/>
        </columns>
        <rows>
                <row>
                    Clave:
                     <textbox hflex="1" value="@{product.id}" readonly="true"/>
                </row>
                <row>
                    Nombre:
                     <textbox id="txtname" value="@{product.name}" hflex="1" tabindex="1" />
                </row>
                <row>
                     Description:
                      <textbox value="@{product.description}" rows="5" hflex="1" tabindex="2" />
                </row>
                <row>
                    <cell colspan="2" style="text-align:center">
                        <hlayout>
                            <button width="100px" id="save" label="Aceptar"/>
                            <button width="100px" label="close"/>
                        </hlayout>
                   </cell>
                </row>
        </rows>
    </grid>
</window>

ProductController.java

public class ProductTypeController extends SelectorComposer {
@WiredVariable
    private ProductTypeService productTypeService;

@Wire
    private Listbox myList;

//methods...

}

Answer 1

This is NOT recommended

1. To avoid concurrency issues (Refer here) For eg. if same controller instance is applied to multiple views, the wired components will point to the last view causing erratic behavior of UI. It is easier to just use different instances instead of coding for concurrency issues and making controller thread safe.
2. To avoid memory leak. For eg. if same controller instance is applied to two completely different views and components from both views are wired in it, then if one of the view is not being used its components wired will still not be released causing memory leak.