Why would I want to use the Appendable interface?

The Appendable interface and its append() methods are implemented in classes that support adding characters to the end of an object, typically a stream. Indirectly used through the Formatter class, you can attach a character, CharSequence, or CharSequence subset. The classes that implement Appendable are BufferedWriter, CharArrayWriter, CharBuffer, FileWriter, FilterWriter, LogStream, OutputStreamWriter, PipedWriter, PrintStream, PrintWriter, StringBuffer, StringBuilder, StringWriter, and Writer.