Java Examples in a Nutshell, 3rd Edition

Manipulating Beans

The ShowBean class of Chapter 11 is a simple beanbox for displaying and experimenting with individual beans. The ShowBean code listed in Example 11-30 is concerned primarily with the creation of a GUI, and the key bean-manipulation methods are handled by a separate Bean class. Now that we’ve seen how to write a bean and its auxiliary classes, we’re ready to tackle this Bean class itself; it is listed in Example 15-10.

An instance of the Bean class represents a single bean and its associated BeanInfo. Bean defines methods for querying and setting bean properties and for querying and invoking bean commands. (It defines a command as a method with no arguments and no return values.) In some ways, Bean can be considered a simplified interface to the BeanInfo class. Note that the java.beans package does not define any class named Bean: JavaBeans are not required to implement any Bean interface or extend any Bean superclass, so we’ve appropriated this class name for our own use here.

The Bean class has a public constructor that uses the java.beans.Introspector class to obtain BeanInfo for the bean object you pass to it. Bean also defines three static factory methods that you can use to instantiate the bean object instead of creating it yourself: forClassName( ) instantiates a named class to create the bean; fromSerializedStream( ) reads a serialized bean object from a java.io.ObjectInputStream (see Chapter 10); and fromPersistentStream( ) uses the JavaBeans persistence ...