Kata Formulation: Copy Program

Description

Consider a simple program that is charged with the task of copying characters typed on a keyboard to a printer. Assume, furthermore, that the implementation platform does not have an operating system that supports device independence. We might conceive of a structure for this:

Figure [above] is a "structure chart". It shows that there are three modules, or subprograms, in the application. The "Copy" module calls the other two. One can easily imagine a loop within the "Copy" module. The body of that loop calls the "Read Keyboard" module to fetch a character from the keyboard, it then sends that character to the "Write Printer" module which prints the character.

extracted from The Dependency Inversion Principle, by Robert C. Martin

Problem

Your task, should you accept it, is to write a program that performs the above-descripted action.

Bear in mind that we are not sure where to 'read' from. Neither where we want to write to.

These are the APIs we want to have:

class ReadKeyboard {
  public boolean hasNext();
  public String  get();
}

class WritePrinter {
  public void print(String message);
}