Question

在主线程中，用户可以在选择获取订单的选项后从控制台发出订单。选择该选项后，我将触发一个线程cook.start（）;负责从队列中吸引客户并准备他们的订单。准备好订单后，我就有了从线程调用的侦听器，并且侦听器仅显示消息。

问题是，即使我的代码循环后，我的主线程也已死了，我无法提供进一步的输入来要求其他命令。

public class Driver {
    private static LinkedBlockingQueue<Customer> waitingCustomer=new LinkedBlockingQueue<Customer>();


    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        OrderPrepared op=new OrderPrepared(waitingCustomer);

        while (true) {
            System.out.println("would you like to place new Order Press Y or N");
            String input = sc.nextLine();
            if ("y".equalsIgnoreCase(input)) {
                Customer customer = null;
                System.out.println("Enter Customer Name");
                String name = sc.nextLine();
                System.out.println("What would you like to order");
                System.out.println(" ");
                System.out.println("Our Menu Card ");
                System.out.println(" ");
                System.out.println("Item Name\t\t" + "     Price\t\t" + "Press to order");
                System.out.println(" ");
                System.out.println("Cheese And Tomato\t\t" + "60\t\t" + "1");
                System.out.println("Margerita        \t\t" + "40\t\t" + "2");
                System.out.println("Burger           \t\t" + "50\t\t" + "3");
                System.out.println("Chicken Fried    \t\t" + "90\t\t" + "4");
                System.out.println(" ");
                System.out.println("Please Press Number to place order");
                int number=sc.nextInt();
                Food food=null;

                switch(number) {
                case 1: 
                    food=new Food("Cheese And Tomato", 60.0d);
                case 2:
                    food=new Food("Margerita", 40.0d);
                case 3:
                    food=new Food("Burger", 50.0d);
                case 4:
                    food=new Food("Chicken Fried", 90.0d);
                }
                Random ran=new Random(709);
                customer=new Customer(name,new Order(ran.nextInt(), food));
                waitingCustomer.add(customer);
                Chef chef=new Chef();
                chef.setChefListener(op);
                chef.setCustomers(waitingCustomer);
                chef.setFood(food);
                chef.start();

            } else {
                break;
            }
        }

    }

}


public class Chef extends Thread {


    Food food;
    ChefListener chefListener;
    LinkedBlockingQueue<Customer> customers;

    public Chef() {

    }
    public Chef(Food piza, ChefListener chefListener, LinkedBlockingQueue<Customer> customers) {
        super();
        this.food = piza;
        this.chefListener = chefListener;
        this.customers = customers;
    }

    @Override
    public void run() {
        // TODO Auto-generated method stub
        for (Customer customer : customers) {
            chefListener.pizzaCooked(customer, food);
            customers.remove();
            System.out.println("customer has been removed from queue");
        }

    }
    public Food getFood() {
        return food;
    }

    public void setFood(Food food) {
        this.food = food;
    }

    public ChefListener getChefListener() {
        return chefListener;
    }

    public void setChefListener(ChefListener chefListener) {
        this.chefListener = chefListener;
    }

    public LinkedBlockingQueue<Customer> getCustomers() {
        return customers;
    }

    public void setCustomers(LinkedBlockingQueue<Customer> customers) {
        this.customers = customers;
    }
}



public class OrderPrepared implements ChefListener{
    Logger logger=Logger.getLogger("OrderPrepared");
    public OrderPrepared(LinkedBlockingQueue<Customer> waitingCustomer) {

    }

    @Override
    public void pizzaCooked(Customer customer, Food food) {
        // TODO Auto-generated method stub
        logger.info(customer.getName()+" "+food.getName() + " has been cooked. Enjoy");

    }

}


Output
import java.util.concurrent.LinkedBlockingQueue;
import java.util.logging.Logger;

public class OrderPrepared implements ChefListener{
    Logger logger=Logger.getLogger("OrderPrepared");
    public OrderPrepared(LinkedBlockingQueue<Customer> waitingCustomer) {
        // TODO Auto-generated constructor stub
    }

    @Override
    public void pizzaCooked(Customer customer, Food food) {
        // TODO Auto-generated method stub
        logger.info(customer.getName()+" "+food.getName() + " has been cooked. Enjoy");

    }

}

Output

would you like to place new Order Press Y or N
Y
Enter Customer Name
Kalis
What would you like to order

Our Menu Card 

Item Name            Price      Press to order

Cheese And Tomato       60      1
Margerita               40      2
Burger                  50      3
Chicken Fried           90      4

Please Press Number to place order
2
would you like to place new Order Press Y or N
customer has been removed from queue
Nov 12, 2019 2:32:45 AM OrderPrepared pizzaCooked
INFO: Kalis Chicken Fried has been cooked. Enjoy

Answer 1

nextInt（）不消耗LF。在nextInt（）之后跟随nextLine（），以便使用行终止符（lf）。没有这个，循环顶部的nextLine将以空行退出。

另请参见Scanner is skipping nextLine() after using next() or nextFoo()?

即使有循环，主线程也会死掉

1 个答案: