[Library class] class LakeLightLibrary{ public ArrayList shelf = new ArrayList(); public LakeLightLibrary() { shelf.add("Book1"); shelf.add("Book2"); shelf.add("Book3"); } public String lendBook(){ Thread thread = Thread.currentThread(); String book = shelf.remove(0); System.out.println(thread.getName() + ": " + book + " lean"); return book; } public void returnBook(String book){ Thread thread =..