Question

On my page I have a drop down whose values are populated based on an enum and the selection sets the value of the enum as well . I now have requirement to display text like “Please select a Value” in the drop down and that is not present in enum.

It is also possible for user to not select any value from drop down .

How can a populate selectOne with this additional text without modifying enum and handle it in the managed bean if user does not select a value (which is legal for user to do so). I have tried various combinations but nothing worked for me .

Here is what I have working which is standard dropdown list populated with different values enum just a standar way.

This is enum here

public enum Fruit {
    APPLE("Apple"), ORANGE("Orange");

    private String label;

    Fruit(String label) {
        this.label = label;
    }

    public String getLabel() {
        return label;
    }

    public void setLabel(String label) {
        this.label = label;
    }   

}

A Managed Bean

import java.util.ArrayList;
import java.util.List;

import javax.annotation.PostConstruct;
import javax.faces.bean.ManagedBean;
import javax.faces.model.SelectItem;

@ManagedBean
public class Simplebean {

    private Fruit selectedFruit;// How would this work if the value is not valid enum .
    private List<SelectItem>fruits = new ArrayList<SelectItem>();

    @PostConstruct
    public void init(){
        for (Fruit fruit : Fruit.values()){
            fruits.add(new SelectItem(fruit,fruit.getLabel()));// How to add a value not part of enum.
        }
    }

    public List<SelectItem> getFruits() {
        return fruits;
    }

    public void setFruits(List<SelectItem> fruits) {
        this.fruits = fruits;
    }

    public Fruit getSelectedFruit() {
        return selectedFruit;
    }

    public void setSelectedFruit(Fruit selectedFruit) {
        this.selectedFruit = selectedFruit;
    }

}

In XHTML

<h:selectOneMenu value="#{simplebean.selectedFruit}">
    <f:selectItems value="#{simplebean.fruits}" />
</h:selectOneMenu>

Answer 1

You can do it as Luggi wrote, but add a the noSelectionOption to the additional <f:selectItem>. And a s suggestion – you don’t need to define the selectItem List List<SelectItem>fruits anymore on the backing bean, you can do it this way:

<h:selectOneMenu value="#{simplebean.selectedFruit}">
    <f:selectItem itemLabel="Select a value" noSelectionOption="true"/>
    <f:selectItems value="#{simplebean.fruits}" var="fruit" itemLabel="#{fruit.label}" itemValue="#{fruit}"/>
</h:selectOneMenu>

And the backing bean without fruits selectItems:

@ManagedBean
public class Simplebean {

    private Fruit selectedFruit;

    public Fruit getSelectedFruit() {
        return selectedFruit;
    }

    public void setSelectedFruit(Fruit selectedFruit) {
        this.selectedFruit = selectedFruit;
    }

    public Fruit[] getFruits() {
        return Fruit.values();
    }
}