(...)
switch (choice) {
        case 1:
          occuped = occuped + 5;
          try {
            command.setContentObject("#increment");
            groupManager.sendGroupcastMessage(command, aGroup);
          }
          catch (IOException e) {
            e.printStackTrace();
          }
          break;
        case 2:
          if (occuped > 0) {
            occuped = occuped - 5;
          }
          try {
            command.setContentObject("#decrement");
            groupManager.sendGroupcastMessage(command, aGroup);
          }
          catch (IOException e) {
            e.printStackTrace();
          }
          break;
        default:
          choice = 0;
          System.out.println("Saindo do programa ...");
          break;
      }
(...)