Design Patterns Java™ Workbook

Prototyping with Clones

To complete the factory design, you have to establish how the prototypical instance variables in a UIKit object will copy themselves. You consider using clone(), a method that every class inherits from Object. However, this method must be used with caution; it does not provide foolproof copying of an object.

CHALLENGE 18.3 Consult the source code for Object.clone() and write down what this method does.

Consider copying an OzTextArea object. When you investigate this class, you see that it is a subclass of JPanel, as Figure 18.2 shows.

Figure 18.2. The OzTextArea class inherits a large number of methods and variables from its superclasses.

Subclassing from JPanel lets OzTextArea objects uniformly wrap their contents ...