JavaFX多線程和控制器類

Question

我想用javafx同時執行多個倒計時定時器。目前使用多線程。現在我正試圖在標籤上打印定時器，以便在屏幕上顯示，但無法這樣做，因爲我無法訪問控制器類來打印它。我如何實現使用我的線程類打印標籤上的計時器值。我的計時器值應該打印在gridpane中的標籤中，所以我從控制器類中獲取約束，然後相應地打印。

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

給你Rdt類回調到時候它代表的變化來執行。這可能是一個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."); 
    } 

    // ... 
} 

從你的控制器類

現在你可以開始與定時器：

public class Controller { 

    @FXML 
    private Label timerLabel ; 

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

一對夫婦旁白的：

1. 這裏不需要創建線程。 Timer類已爲創建一個後臺線程，因此它將在後臺線程中運行而不顯式創建一個後臺線程。

2. 你真的在很多地方重新發明輪子。例如，標準庫已經有了一個Duration class，它可以用來表示分鐘和秒，並且已經爲您實現了所有的算術。試想一下：

   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); 
       } 
   } 
   

同樣，在DateTimeFormatter類知道如何很好地格式化時間作爲字符串，所以從控制器你會做：

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