[Ch15b] More readable output

    ExecutorService executor = Executors.newFixedThreadPool(4);

    for (int i = 0; i < 5; i++) {

      executor.execute(new Chatty(chatHistory));

      executor.execute(new ChatReader(chatHistory));

      executor.execute(new ChatReader(chatHistory));

      executor.execute(new ChatReader("Reader 1", chatHistory));

      executor.execute(new ChatReader("Reader 2", chatHistory));

    }

    executor.shutdown();

  }

}

class ChatReader implements Runnable {

  private String name;

  private ChatHistory chatHistory;

  public ChatReader(ChatHistory chatHistory) {

  public ChatReader(String name, ChatHistory chatHistory) {

    this.name = name;

    this.chatHistory = chatHistory;

  }

  @Override

  public void run() {

    for (Chat chat : chatHistory.getHistory()) {

      System.out.println(chat);

      System.out.println(name + " read: " + chat);

    }

  }

}