How to bind data with checkbox list in JSF?

I've the following code in my edit user screen

<h:selectManyCheckbox id="selectedGroups" value="#{usersController.selectedGroups}">
                <f:selectItems value="#{usersController.groupsList}" var="item" itemLabel="#{item.groupname}" itemValue="#{item.groupid}" />
            </h:selectManyCheckbox>

I've user groups list with all the groups in it, and I've selectedGroups list with the groups that are enabled for the user. But, on the edit screen, they are not showing selected by default. What am I missing? Is this not the right way to bind selected many checkboxe开发者_Go百科s?

An item value of the groupsList will be preselected only when equals() method has returned true for at least one item in the selectedGroups.

Assuming that groupid is a Long, then the selectedGroups should return a List<Long> containing the values to be preselected.

Following code will work perfectly for request scope bean...

xhml code....

 <h:selectManyCheckbox binding="#{Page1.chk_1}">
        <f:selectItem binding="#{Page1.chk_1_options}"/>
 </h:selectManyCheckbox>

Java code....

HtmlSelectManyCheckbox chk_1 = new HtmlSelectManyCheckbox();
UISelectItems chk_1_options = new UISelectItems();

public HtmlSelectManyCheckbox getChk_1() {
    return chk_1;
}

public void setChk_1(HtmlSelectManyCheckbox chk_1) {
    this.chk_1 = chk_1;
}

public UISelectItems getChk_1_options() {
    if (chk_1_options.getValue() == null) {
        List<SelectItem> lst_chk_options = new ArrayList<SelectItem>();
        lst_chk_options.add(new SelectItem(1, "Label1"));
        lst_chk_options.add(new SelectItem(2, "Label2"));
        chk_1_options.setValue(lst_chk_options);
    }
    return chk_1_options;
}

public void setChk_1_options(UISelectItems chk_1_options) {
    this.chk_1_options = chk_1_options;
}

If you want for session scope then reply, because binding elements in session scope giving problems in some cases...