JSF/SEAM: How to pre-select checkboxes in a form

I have a form where i have to preselect some checkboxes. How is that possible with jsf/seam? In plain html开发者_运维知识库 you would just add the "checked" (or checked="checked") as attribute to the checkboxes. But with f:selectItems I have no clue...also the Object "SelectItem" does not provide any setter for this...

You need to preset them in the property behind the component's value attribute as you usually do for every UIInput component. You can do that in the bean's constructor or initialization block.

Here's a basic example:

<h:selectManyCheckbox value="#{bean.selectedItems}">
    <f:selectItems value="#{bean.selectItems}" />
</h:selectManyCheckbox>

Bean:

private List<String> selectedItems; // +getter +setter.
private List<SelectItem> selectItems; // +getter.

public Bean() {
    // Preset the selected items.
    this.selectedItems = new ArrayList<String>();
    this.selectedItems.add("valueToBePreselected1");
    this.selectedItems.add("valueToBePreselected2");
    // Those values should be exactly the same as one of the SelectItem values.
    // I.e. the Object#equals() must return true for any of them.
}

Populate the property you use in "value" before rendereing the page (for example using a phase listener)

<h:selectManyCheckbox value="#{selectManyCheckBoxBean.selectedItems}">
    <f:selectItem itemLabel="India" itemValue="India" />
    <f:selectItem itemLabel="China" itemValue="China" />
    <f:selectItem itemLabel="Germany" itemValue="Germany" />
    <f:selectItem itemLabel="USA" itemValue="USA" />
</h:selectManyCheckbox>