Struts 2 Sort tag example

Download It – Struts2-Sort-Tag-Example.zip

Struts 2 sort tag is used to sort a List using a java.util.Comparator. In this tutorials, you will create 6 Person objects and add all into an ArrayList, and use the sort tag to sort the ArrayList based on the Person’s property.

To use this Struts 2 sort tag, you have to understand how java.util.Comparator work, please read this article – Java object sorting with Comparator.

1. Person object

Create a Person object with “firstName”, “lastName” and “age” properties.

Person.java

package com.mkyong.common;
 
public class Person{
 
	private String firstName;
	private String lastName;
	private int age;
 
	public Person(String firstName, String lastName, int age) {
		super();
		this.firstName = firstName;
		this.lastName = lastName;
		this.age = age;
	}
 
	public String getFirstName() {
		return firstName;
	}
	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}
	public String getLastName() {
		return lastName;
	}
	public void setLastName(String lastName) {
		this.lastName = lastName;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
}

2. Comparator

Create 2 Comparator classes, to sort the Person’s “firstName” and “age” property.

FirstNameComparator.java

package com.mkyong.common;
 
import java.util.Comparator;
import com.mkyong.common.Person;
 
public class FirstNameComparator implements Comparator<Person> {
 
	public int compare(Person p1, Person p2) {
 
		String firstName1 = p1.getFirstName().toUpperCase();
		String firstName2 = p2.getFirstName().toUpperCase();
 
		return firstName1.compareTo(firstName2);
	}
}

AgeComparator.java

package com.mkyong.common;
 
import java.util.Comparator;
import com.mkyong.common.Person;
 
public class AgeComparator implements Comparator<Person> {
 
	public int compare(Person p1, Person p2) {
 
		return p1.getAge() - p2.getAge();
 
	}	
}

3. Action

Action class, initialize 6 Person objects, and add it into an ArrayList.

package com.mkyong.common.action;
 
import java.util.ArrayList;
import java.util.List;
 
import com.mkyong.common.Person;
import com.opensymphony.xwork2.ActionSupport;
 
public class SortTagAction extends ActionSupport{
 
	private List<Person> persons = new ArrayList<Person>();
 
	public String execute() {
 
		Person p1 = new Person("C-First", "C-Last", 40);
		Person p2 = new Person("A-First", "A-Last", 20);
		Person p3 = new Person("B-First", "B-Last", 10);
		Person p4 = new Person("F-First", "F-Last", 33);
		Person p5 = new Person("E-First", "E-Last", 22);
		Person p6 = new Person("D-First", "D-Last", 11);
 
		persons.add(p1);
		persons.add(p2);
		persons.add(p3);
		persons.add(p4);
		persons.add(p5);
		persons.add(p6);
 
		return SUCCESS;
	}
 
	public List<Person> getPersons() {
		return persons;
	}
	public void setPersons(List<Person> persons) {
		this.persons = persons;
	}
}

4. Sort tag example

A JSP page to show the use of sort tag to sort the List with “FirstNameComparator” and “AgeComparator“.

sort.jsp

<%@ taglib prefix="s" uri="/struts-tags" %>
 <html>
<head>
</head>
 
<body>
<h1>Struts 2 Sort tag example</h1>
 
<s:bean name="com.mkyong.common.FirstNameComparator" var="firstNameComparator" />
<s:bean name="com.mkyong.common.AgeComparator" var="ageComparator" />
 
<table>
<tr>
<td>
1. Display all persons (unsort).
<ol>
<s:iterator value="persons">
     <li><s:property value="firstName" />, 
         <s:property value="lastName" />, 
         <s:property value="age" />
     </li>
</s:iterator>
</ol>
</td>
 
<td>
2. Display all persons (sort with firstName).
<s:sort comparator="#firstNameComparator" source="persons">
<ol>
<s:iterator>
     <li><s:property value="firstName" />, 
         <s:property value="lastName" />, 
         <s:property value="age" />
     </li>
</s:iterator>
</ol>
</s:sort>
</td>
</tr>
 
<tr>
<td colspan="2">
3. Display all persons (sort with age).
<s:sort comparator="#ageComparator" source="persons">
<ol>
<s:iterator>
     <li><s:property value="firstName" />, 
         <s:property value="lastName" />, 
         <s:property value="age" />
     </li>
</s:iterator>
</ol>
</s:sort>
</td>
</tr>
</table>
 
</body>
</html>

5. struts.xml

Link it ~

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
 
<struts>
 	<constant name="struts.devMode" value="true" />
	<package name="default" namespace="/" extends="struts-default">
		<action name="sortTagAction" 
			class="com.mkyong.common.action.SortTagAction" >
			<result name="success">pages/sort.jsp</result>
		</action>
	</package>
</struts>