Decorator (Filter, Wrapper)

Solution: Combine inheritance and composition. By making an object that both subclasses from another class and holds an instance of the class, can add new behavior while referring all other behavior to the original class.

Example Input Streams in the Java I/O System

	// a buffered input stream is-an input stream
class BufferedInputStream extends InputStream {

	public BufferedInputStream (InputStream s) { data = s; }
	...

		// and a buffered input stream has-an input stream
	private InputStream data;
}