Question

我正在尝试使用javafx同时执行多个倒计时器。目前使用多线程。现在我试图在标签上打印定时器，以便在屏幕上显示，但无法这样做因为我无法访问控制器类来打印它。如何使用我的线程类在标签上实现打印计时器值。我的计时器值应该打印在gridpane中的标签中，所以我从控制器类中获取约束，然后相应地打印。

package tabapplication;
import java.util.Timer;
import java.util.TimerTask;
import tabapplication.TabApplication;
import tabapplication.FXMLDocumentController;
class Rdt implements Runnable {
   private Thread t;
   private String threadName;

   Rdt( String name){
       threadName = name;
       System.out.println("Creating " +  threadName );
   }
   public void run() {
      System.out.println("Running " +  threadName );
      try {
          final Timer timer = new Timer();
        timer.scheduleAtFixedRate(new TimerTask() {
            int s = 60;
            int m=30;
            public void run() {
                s--;
                if(s<0 &&  m>0)
                {m--;
                s=59;
                }
                if(s<10)
                {  System.out.println(Integer.toString(m)+":"+0+Integer.toString(s)); }
                else
                {System.out.println(Integer.toString(m)+":"+Integer.toString(s));}


                if(m==0 && s==0)
                    timer.cancel();
            }
        }, 0, 10);
            Thread.sleep(50);
     } catch (InterruptedException e) {
         System.out.println("Thread " +  threadName + " interrupted.");
     }
     System.out.println("Thread " +  threadName + " exiting.");
   }

   public void start ()
   {
      System.out.println("Starting " +  threadName );
      if (t == null)
      {
         t = new Thread (this, threadName);
         t.start ();
      }
   }
   public static void main(String args[]) {

      Rdt R1 = new Rdt( "Thread-1");
      Thread obj1=new Thread(R1);
      obj1.start();

      Rdt R2 = new Rdt( "Thread-2");
     Thread obj2=new Thread(R2);
     obj2.start();
   }   
}

Answer 1

为Rdt类提供一个回调函数，以便在它代表更改时执行。这可以是Consumer<String>的形式，例如：

class Rdt implements Runnable {
   private Thread t;
   private String threadName;

   private Consumer<String> callback ;

   Rdt( String name, Consumer<String> callback){
       threadName = name;
       System.out.println("Creating " +  threadName );
       this.callback = callback ;
   }
   public void run() {
      System.out.println("Running " +  threadName );
      try {
          final Timer timer = new Timer();
        timer.scheduleAtFixedRate(new TimerTask() {
            int s = 60;
            int m=30;
            public void run() {
                s--;
                if(s<0 &&  m>0)
                {m--;
                s=59;
                }
                if(s<10)
                {  callback.accept(Integer.toString(m)+":"+0+Integer.toString(s)); }
                else
                {callback.accept(Integer.toString(m)+":"+Integer.toString(s));}


                if(m==0 && s==0)
                    timer.cancel();
            }
        }, 0, 10);
            Thread.sleep(50);
     } catch (InterruptedException e) {
         System.out.println("Thread " +  threadName + " interrupted.");
     }
     System.out.println("Thread " +  threadName + " exiting.");
   }

   // ...
}

现在，您可以从控制器类中启动计时器：

public class Controller {

    @FXML
    private Label timerLabel ;

    @FXML
    private void startTimer() {
        Rdt timer = new Rdt("Timer-1", timerLabel::setText);
        timer.run();
    }
}

一些旁白：

此处无需创建线程。 Timer类已经为您创建了一个后台线程，因此这将在后台线程中运行，而不会显式创建一个。

你真的在很多地方重新发明轮子。例如，标准库已经有一个Duration class，它可以用来表示分钟和秒，并且已经为你实现了所有的算术运算。考虑：

public class Rdt {

    private String name ;

    private Consumer<Duration> callback ;

    private Duration time ;

    public Rdt(String name, Consumer<Duration> callback) {
        this.name = name ;
        this.callback = callback ;
    }

    public void startTimer() {
        Timer timer = new Timer();
        time = Duration.ofMinutes(30);
        timer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                time = time.minusSeconds(1);
                callback.accept(time);
                if (time.isZero()) {
                    timer.cancel();
                }
            }
        }, 0, 10);
    }
}

同样地，DateTimeFormatter类知道如何将时间格式化为字符串，所以从控制器中你可以做到：

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("mm:ss");
Rdt timer = new Rdt("Timer-1", time -> timerLabel.setText(formatter.format(time)));
timer.start();

JavaFX多线程和控制器类

1 个答案: