如何创建像电话一样的秒/毫秒计时器？

Question

我对 Java 编码比较陌生，可以被视为新手。然而，我还有很多东西要学，我正在尝试创建一个带有倒计时和秒表的迷你乘法游戏。我希望秒表在倒计时说“开始！”后以秒和毫秒为单位计数。我想显示玩家解决问题花了多长时间。我尝试查找有关如何初始化秒表的教程，但是它似乎没有初始化。我知道这一点是因为我打印了值，secondsPassed 最后输出为 0。 谁能帮我修复我的代码，这样我就可以在“Go！”之后的几秒和几毫秒内启动一个计时器。并在游戏完成后显示时间？ 谢谢。

import java.util.Scanner;
import java.util.Timer;
import java.util.TimerTask;

public class Mathgame {


    public static int secondsPassed = 0;

    Timer timer = new Timer();
    TimerTask task = new TimerTask() {

        public void run() {

            secondsPassed++;

        }

    };


    public void start() {


        timer.scheduleAtFixedRate(task,1000,1000);
    }

    public static void main(String[] args) {



        Scanner input = new Scanner(System.in);

        System.out.println("Welcome to 'The Math Game!' Please chose whether you would like to play or not by inputting 'yes' or 'no'.");

        String x = input.nextLine();




        if(x.equals ("no")) {
            System.out.println("Ok! Maybe next time!");

            System.exit(1);
        } else {

            System.out.println("OK! We are starting the game in...");

                    System.out.println("3");

                    try {
                        Thread.sleep(1000); 
                    } catch(InterruptedException ex){

                        System.exit(0);
                    }

                    System.out.println("2");
                    try {
                        Thread.sleep(1000);

                    } catch(InterruptedException ex) {
                        System.exit(0);
                    }

                    System.out.println("1!!");

                    try {
                        Thread.sleep(1000);

                    } catch(InterruptedException ex) {
                        System.exit(0);
                    }


                    System.out.println("Go!");

                    System.out.println("Your timer started!");



                    System.out.println(secondsPassed);


        }

    }

}

Answer 1

我不知道你想做什么，但我对你的代码做了一些修改，使它更有趣和更干净......

public class Mathgame {

    // it is not necessary do it static
    public int secondsPassed = 0;

    //alternatively you can use  Timer timer = new Timer(true); if you want to stop timer immediately after method main is finished
    Timer timer = new Timer();
    TimerTask task = new TimerTask() {

        public void run() {

            secondsPassed++;
            // your timer will run this method every 1 sec, so you need to put output here if you want to see changes
            System.out.println("Running my task again. secondsPassed is " +secondsPassed);
        }

    };

    public void start() {
        //this timmer will run your task every 1000ms (1 second) and will start in 1000ms (1 second) after start is called
        timer.scheduleAtFixedRate(task, 1000, 1000);
    }

    // this is main method so it is better to throw exceptions upper then handler them without output
    public static void main(String[] args) throws InterruptedException {


        Scanner input = new Scanner(System.in);

        System.out.println("Welcome to 'The Math Game!' Please chose whether you would like to play or not by inputting 'yes' or 'no'.");

        String x = input.nextLine();

        // it is better to check for 'yes' than for 'no' this is good practice
        if (x.equalsIgnoreCase("yes") || x.equalsIgnoreCase("y")) {

            System.out.println("OK! We are starting the game in...");

            System.out.println("3");

            Thread.sleep(1000);

            System.out.println("2");

            Thread.sleep(1000);

            System.out.println("1!!");

            Thread.sleep(1000);

            System.out.println("Go!");

            //starting your timer, we have to create object of your class first and then run method start
            Mathgame mathgame = new Mathgame();
            mathgame.start();

            System.out.println("Your timer started!");

            //main is finished however there is timer thread which is still working
            // if you want to stop timer immediately after main then you need to build it as 'Timer timer = new Timer(true);'
            // in that case you may put here extra sleep and see how timer is working

            //let wait until timer will count 10 sec
            Thread.sleep(10000);
            //you can check secondsPassed from main too
             System.out.println("This is called from main. secondsPassed value is " + mathgame.secondsPassed);

            System.out.println("Method main is finished");
        }
    }
}