Jakarta Commons Cookbook

3.5. Accessing Nested Bean Properties

Problem

You need to access a nested bean property.

Solution

Use PropertyUtils.getNestedProperty() to retrieve a nested bean property. Use a period as a delimiter to identify nested bean properties; one.two.three.four refers to a property nested three levels deep—the four property of the three property of the two property of the one property. The following example accesses a nested bean property on a Person bean, author.name:

import org.apache.commons.beanutils.PropertyUtils;

Book book = new Book( );
book.setName( "Emerson's Essays" );

Person author = new Person( );
author.setName( "Ralph Waldo Emerson" );
book.setAuthor( author );

String authorName = (String) PropertyUtils.getNestedProperty(book, "author.name");
System.out.println( "authorName" );This example retrieves the name 
property of the author property on the Book object, printing "Ralph 
Waldo Emerson".

Discussion

The author property of Book is a Person bean with a name property; calling getNestedProperty( ) with author.name retrieves the simple property author from Book and the property name, which is nested in the author property. Figure 3-3 shows the Book and Person beans that were used in the previous example.

Figure 3-3. Structure of two simple beans: Book and Person

The following example demonstrates a combination of getSimpleProperty( ) and getNestedProperty( ), retrieving a book name ...