javac的访问者模式2

（5）Printer

/**
 * A combined type/symbol visitor for generating non-trivial(有意义的） localized string
 * representation of types and symbols.
 *
 */
public abstract class Printer implements Type.Visitor<String, Locale>, Symbol.Visitor<String, Locale>
    ...}　　

这个类继承实现了Type.Visitor与Symbol.Visitor接口