Basic definitions for selectBooleanCheckbox and selectManyCheckbox would be as follows:

<p:selectBooleanCheckbox
  value="#{selectCheckboxBean.selectedValue}" />

<p:selectManyCheckbox 
  value="#{selectCheckboxBean.selectedCountries}">
  <f:selectItem itemLabel="Turkey" itemValue="Turkey" />
  <f:selectItem itemLabel="Germany" itemValue="Germany" />
  <f:selectItem itemLabel="Switzerland" itemValue="Switzerland" />
</p:selectManyCheckbox>

Adding labels to the checkbox is easy with the itemLabel attribute. The itemLabel attribute displays a label next to the checkbox:

<p:selectBooleanCheckbox 
  value="#{selectCheckboxBean.selectedValue}"
  itemLabel="#{msg['selectBooleanCheckbox.label']}" />

The text that will be rendered right next to the checkbox component with the itemLabel attribute can also be clicked to select/deselect the checkbox. The msg resource bundle variable given in the example is defined in faces-config.xml.

The direction of contents of the selectManyCheckbox component can be changed from the default horizontal rendering to vertical by setting the layout attribute with the pageDirection value. The output for both horizontal and vertical rendering of the example given in the basic definition is shown in the following screenshot:

The layout of selectManyCheckbox can be customized with its columns attribute, which would specify the maximum number of allowed columns. When it's exceeded the number of SelectItem elements given, a new row will be created automatically.

It's also possible to get the state of the checkbox at the client-side via JavaScript. To achieve this, the widgetVar attribute needs to be specified to the component. The widgetVar attribute defines the client-side variable, which has various responsibilities, such as progressive enhancement of the markup and communication with the server-side via AJAX. It can also be used directly from the JavaScript code as follows:

<p:selectBooleanCheckbox 
  value="#{selectCheckboxBean.selectedValue}"
  widgetVar="mySelection" />

<p:commandLink value="Alert Selection" 
  onclick="alert(PF('mySelection').isChecked());" />

Within the alert method of the onclick event of commandLink (a client-side JavaScript call), the state will be retrieved by the mySelection.isChecked() code section. The checkbox component is being accessed by mySelection, which is the name of the client-side widget variable of the checkbox.

<p:selectBooleanCheckbox
  value="#{selectCheckboxBean.selectedValue}">
  <p:ajax update="growl"
    listener="#{selectCheckboxBean.addMessage}" />
</p:selectBooleanCheckbox>

public void addMessage() {
  String summaryKey =
    selectedValue ? "checkbox.checked" : "checkbox.unchecked";
  MessageUtil.addInfoMessage(summaryKey);
}

For details about the MessageUtil class, see the Internationalization (i18n) and Localization (L10n) recipe in Chapter 1, Getting Started with PrimeFaces.