see also Writer class
■ FilterWriter is an abstract character output stream class with non-abstract methods. Its methods merely pass data along, unfiltered, if the methods are not overridden..
■ FilterWriter is provided as a convenience superclass for writing new filtering classes. It is there so you do not have to override all of Writer's methods. To create your own new filtered character output stream, you would simply extend FilterWriter and override just selected methods, adding your own special filtering actions to them .