UISelectItems Properties

UISelectItems components are children of UISelectMany and UISelectOne components. Each UISelectItems component is composed of either a set of SelectItem instances or a set of SelectItemGroup instances. As described in Using the selectItems Tag, a SelectItemGroup is composed of a set of SelectItem instances. This section describes how to write the properties for selectItems tags containing SelectItem instances and for selectItems tags containing SelectItemGroup instances.

Properties for SelectItems Composed of SelectItem Instances

Using the selectItems Tag describes how the newsletters list of the Duke’s Bookstore application is populated using the application configuration resource file. You can also populate the SelectItems with SelectItem instances programmatically in the backing bean. This section explains how to do this.

In your backing bean, you create a list that is bound to the SelectItem component. Then you define a set of SelectItem objects, set their values, and populate the list with the SelectItem objects. Here is an example code snippet that shows how to create a SelectItems property:

import javax.faces.component.SelectItem;
...
protected ArrayList options = null;
protected SelectItem newsletter0 =
     new SelectItem("200", "Duke’s Quarterly", "");
...
//in constructor, populate the list
options.add(newsletter0);
options.add(newsletter1);
options.add(newsletter2);
...
public SelectItem getNewsletter0(){
    return newsletter0;
}

void setNewsletter0(SelectItem firstNL) {
    newsletter0 = firstNL;
}
// Other SelectItem properties

public Collection[] getOptions(){
    return options;
}
public void setOptions(Collection[] options){
    this.options = new ArrayList(options);
}

The code first initializes options as a list. Each newsletter property is defined with values. Then, each newsletter SelectItem is added to the list. Finally, the code includes the obligatory setOptions and getOptions accessor methods.

Properties for SelectItems Composed of SelectItemGroup Instances

The preceding section explains how to write the bean property for a SelectItems component composed of SelectItem instances. This section explains how to change the example property from the preceding section so that the SelectItems is composed of SelectItemGroup instances.

Let’s separate the newsletters into two groups: One group includes Duke’s newsletters, and the other group includes the Innovator’s Almanac and Random Ramblings newsletters.

In your backing bean, you need a list that contains two SelectItemGroup instances. Each SelectItemGroup instance contains two SelectItem instances, each representing a newsletter:

import javax.faces.model.SelectItemGroup;
...
private ArrayList optionsGroup = null;

optionsGroup = new ArrayList(2);

private static final SelectItem options1[] = {
    new SelectItem("200", "Duke’s Quarterly", "");
    new SelectItem("202",
         "Duke’s Diet and Exercise Journal", "");
};
private static final SelectItem options2[] = {
    new SelectItem("201", "Innovator’s Almanac", "");
    new SelectItem("203", "Random Ramblings", "");
};

SelectItemGroup group1 =
     new SelectItemGroup("Duke’s", null, true, options1);
SelectItemGroup group2 =
    new SelectItemGroup("General Interest", null, true,
         options2);

optionsGroup.add(group1);
optionsGroup.add(group2);
...
public Collection getOptionsGroup() {
    return optionsGroup;
}
 public void setOptionsGroup(Collection newGroupOptions) {
    optionsGroup = new ArrayList(newGroupOptions);
}

The code first initializes optionsGroup as a list. The optionsGroup list contains two SelectItemGroup objects. Each object is initialized with the label of the group appearing in the list or menu; a value; a Boolean indicating whether or not the label is disabled; and an array containing two SelectItem instances. Then each SelectItemGroup is added to the list. Finally, the code includes the setOptionsGroup and getOptionsGroup accessor methods so that the tag can access the values. The selectItems tag references the optionsGroup property to get the SelectItemGroup objects for populating the list or menu on the page.