Jakarta Struts Cookbook

3.3. Displaying Indexed Properties

Problem

On a JSP page, you need to access data from an indexed property of an object.

Solution

Use bean.property[ index ] to access the indexed value, as shown in Example 3-1.

Example 3-1. Accessing indexed properties

<@taglib uri=http://jakarta.apache.org/struts/tags-bean" prefix="bean"%>

<ul>
  <li><bean:write name="foo" property="bar.baz[0]"/></li>
  <li><bean:write name="foo" property="bar.baz[1]"/></li>
  <li><bean:write name="foo" property="bar.baz[2]"/></li>
</ul>

JSTL supports access to indexed properties, as shown in Example 3-2.

Example 3-2. Accessing indexed properties (JSTL)

<@taglib uri="http://java.sun.com/jstl/core" prefix="c"%>

<ul>
  <li><c:out value="${foo.bar.baz[0]}"/></li>
  <li><c:out value="${foo.bar.baz[1]}"/></li>
  <li><c:out value="${foo.bar.baz[1]}"/></li>
</ul>

Discussion

Indexed properties are one of the most misunderstood aspects of the Struts tags. An indexed property is a JavaBean property that represents a set of values, not a single scalar value. Indexed properties are accessed using a getter method of the following form:

public Foo getSomeProperty (int index) { ... }

Likewise, indexed properties are set using a setter method of this form:

public void setFoo(int index, Foo someProperty) { ... }

Consider a JavaBean representing a calendar. The CalendarHolder class shown in Example 3-3 has a nested property representing the months in a calendar named monthSet.

Example 3-3. Calendar JavaBean

package com.oreilly.strutsckbk; public class CalendarHolder ...