JSF 2 dropdown box example

2022-10-09 22:24:23

In JSF, <h:selectOneMenu /> tag is used to render a dropdown box – HTML select element with “size=1” attribute.

//JSF...

<h:selectOneMenu value="#{user.favCoffee1}">

   	<f:selectItem itemValue="Cream Latte" itemLabel="Coffee3 - Cream Latte" />

   	<f:selectItem itemValue="Extreme Mocha" itemLabel="Coffee3 - Extreme Mocha" />

   	<f:selectItem itemValue="Buena Vista" itemLabel="Coffee3 - Buena Vista" />

</h:selectOneMenu>

//HTML output...

<select name="j_idt6:j_idt8" size="1">

	<option value="Cream Latte">Coffee3 - Cream Latte</option>

	<option value="Extreme Mocha">Coffee3 - Extreme Mocha</option>

	<option value="Buena Vista">Coffee3 - Buena Vista</option>

</select>

`h:selectOneMenu` example

A JSF 2.0 example to show the use of “h:selectOneMenu” tag to render a dropdow box, and populate the data in 3 different ways :

Hardcoded value in “f:selectItem” tag.
Generate values with a Map and put it into “f:selectItems” tag.
Generate values with an Object array and put it into “f:selectItems” tag, then represent the value with “var” attribute.

1. Backing Bean

A backing bean to hold and generate data for the dropdown box values.

package com.mkyong;

import java.io.Serializable;

import java.util.LinkedHashMap;

import java.util.Map;

import javax.faces.bean.ManagedBean;

import javax.faces.bean.SessionScoped;

@ManagedBean(name="user")

@SessionScoped

public class UserBean implements Serializable{

	public String favCoffee1;

	public String favCoffee2;

	public String favCoffee3;

	public String getFavCoffee1() {

		return favCoffee1;

	}

	public void setFavCoffee1(String favCoffee1) {

		this.favCoffee1 = favCoffee1;

	}

	public String getFavCoffee2() {

		return favCoffee2;

	}

	public void setFavCoffee2(String favCoffee2) {

		this.favCoffee2 = favCoffee2;

	}

	public String getFavCoffee3() {

		return favCoffee3;

	}

	public void setFavCoffee3(String favCoffee3) {

		this.favCoffee3 = favCoffee3;

	}

	//Generated by Map

	private static Map<String,Object> coffee2Value;

	static{

		coffee2Value = new LinkedHashMap<String,Object>();

		coffee2Value.put("Coffee2 - Cream Latte", "Cream Latte"); //label, value

		coffee2Value.put("Coffee2 - Extreme Mocha", "Extreme Mocha");

		coffee2Value.put("Coffee2 - Buena Vista", "Buena Vista");

	}

	public Map<String,Object> getFavCoffee2Value() {

		return coffee2Value;

	}

	//Generated by Object array

	public static class Coffee{

		public String coffeeLabel;

		public String coffeeValue;

		public Coffee(String coffeeLabel, String coffeeValue){

			this.coffeeLabel = coffeeLabel;

			this.coffeeValue = coffeeValue;

		}

		public String getCoffeeLabel(){

			return coffeeLabel;

		}

		public String getCoffeeValue(){

			return coffeeValue;

		}

	}

	public Coffee[] coffee3List;

	public Coffee[] getFavCoffee3Value() {

		coffee3List = new Coffee[3];

		coffee3List[0] = new Coffee("Coffee3 - Cream Latte", "Cream Latte");

		coffee3List[1] = new Coffee("Coffee3 - Extreme Mocha", "Extreme Mocha");

		coffee3List[2] = new Coffee("Coffee3 - Buena Vista", "Buena Vista");

		return coffee3List;

	}

}

2. JSF Page

A JSF page to demonstrate the use “h:selectOneMenu” tag.

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"

"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml"

      xmlns:h="http://java.sun.com/jsf/html"

      xmlns:f="http://java.sun.com/jsf/core"

      >

    <h:body>

    	<h1>JSF 2 dropdown box example</h1>

    	<h:form>

	    1. Hard-coded with "f:selectItem" :

   		<h:selectOneMenu value="#{user.favCoffee1}">

   			<f:selectItem itemValue="Cream Latte" itemLabel="Coffee3 - Cream Latte" />

   			<f:selectItem itemValue="Extreme Mocha" itemLabel="Coffee3 - Extreme Mocha" />

   			<f:selectItem itemValue="Buena Vista" itemLabel="Coffee3 - Buena Vista" />

   		</h:selectOneMenu>

		<br /><br />

	    2. Generated by Map :

   		<h:selectOneMenu value="#{user.favCoffee2}">

   			<f:selectItems value="#{user.favCoffee2Value}" />

   		</h:selectOneMenu>

	        <br /><br />

	    3. Generated by Object array and iterate with var :

   		<h:selectOneMenu value="#{user.favCoffee3}">

   			<f:selectItems value="#{user.favCoffee3Value}" var="c"

   			itemLabel="#{c.coffeeLabel}" itemValue="#{c.coffeeValue}" />

   		</h:selectOneMenu>

	        <br /><br />

    	        <h:commandButton value="Submit" action="result" />

	        <h:commandButton value="Reset" type="reset" />

    	</h:form>

    </h:body>

</html>

result.xhtml…

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"

"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml"

      xmlns:h="http://java.sun.com/jsf/html"

      >

    <h:body>

    	<h1>JSF 2 dropdown box example</h1>

    	<h2>result.xhtml</h2>

    	<ol>

    		<li>user.favCoffee1 : #{user.favCoffee1}</li>

    		<li>user.favCoffee2 : #{user.favCoffee2}</li>

    		<li>user.favCoffee3 : #{user.favCoffee3}</li>

    	</ol>

    </h:body>

</html>

3. Demo

When “submit” button is clicked, link to “result.xhtml” page and display the submitted dropdown box values.

How to pre-select a dropdown box value?

The value of “f:selectItems” tag is selected if it matched to the “value” of “h:selectOneMenu” tag. In above example, if you set “favCoffee1″ property to “Extreme Mocha” :

@ManagedBean(name="user")

@SessionScoped

public class UserBean{

	public String favCoffee1 = "Extreme Mocha";

	//...

The “favCoffee1″ dropdown box, values “Extreme Mocha” is selected by default.

码农公寓

h:selectOneMenu example