等到線程完成

Question

主類：

producer p = new producer(); 
food me = new food(); 
me.eat(times,p); 
....>Rest of Code<....... 

其他類：

class food { 

    public int times; 
    public int food; 
    public boolean canget=false; 
    boolean done=false; 



    void eat(int times,producer p){ 

     this.times = times; 
     p.produce(this); 
     consumer pe = new consumer(); 
     pe.consume(this); 


    } 

    synchronized void add(int n){ 
     while(canget) { 
      try { 
       wait(); 
      } catch (Exception e) { 
       System.out.println("Something nasty happened"); 
      } 
     } 

     this.food = n; 
     System.out.println("Produced food '"+n+"'"); 
     canget = true; 
     notify(); 
    } 
    synchronized int get(){ 
     while (!canget){ 
      try{ 
       wait(); 
      }catch (Exception e) { 
       System.out.println("Something Nasty happened"); 
      } 
     } 
     canget = false; 
     notify(); 
     System.out.println("Eaten food '"+this.food+"'"); 
     return this.food; 
    } 

} 

class producer implements Runnable{ 
    int times; 
    food f; 
    boolean done; 

    boolean done(Thread t) { 
     return done; 
    } 

    void produce(food F){ 
     times=F.times; 
     f=F; 
     Thread t = new Thread(this); 
     t.start(); 



     } 


    public void run() { 
     while(this.times-- > 0){ 
      f.add(times); 

     } 

    } 
} 

class consumer implements Runnable{ 

    int times; 
    food f; 

    void consume(food F){ 
     times=F.times; 
     f=F; 
     Thread t = new Thread(this); 
     t.start(); 
    } 

    public void run() { 
     while(this.times-- > 0){ 
      f.get(); 
     } 
    } 
} 

該語句後：

me.eat(times,p); 

的代碼的其餘部分正在運行，但我想，此前線程由food，producer和consumer完成。我怎樣才能做到這一點？

Answer 1

您可以使用CountDownLatch讓生產者和消費者在完成時發出信號，並在主代碼中等待該信號。

主要代碼：

int times = 3; 

CountDownLatch completion = new CountDownLatch(2); 

producer p = new producer(completion); 
food me = new food(completion); 
me.eat(times, p); 


try { 
    completion.await(); 
} catch (InterruptedException e) { 
    e.printStackTrace(); 
} 

System.out.println("Done"); 

更新類：

class food { 

    public int times; 
    public int food; 
    public boolean canget = false; 
    private CountDownLatch completion; 

    public food(CountDownLatch completion) { 
     this.completion = completion; 
    } 

    void eat(int times, producer p) { 
     this.times = times; 
     p.produce(this); 
     consumer pe = new consumer(completion); 
     pe.consume(this); 
    } 

    synchronized void add(int n) { 
     while (canget) { 
      try { 
       wait(); 
      } catch (Exception e) { 
       System.out.println("Something nasty happened"); 
      } 
     } 

     this.food = n; 
     System.out.println("Produced food '" + n + "'"); 
     canget = true; 
     notify(); 
    } 

    synchronized int get() { 
     while (!canget) { 
      try { 
       wait(); 
      } catch (Exception e) { 
       System.out.println("Something Nasty happened"); 
      } 
     } 
     canget = false; 
     notify(); 
     System.out.println("Eaten food '" + this.food + "'"); 
     return this.food; 
    } 

} 

class producer implements Runnable { 
    int times; 
    food f; 
    boolean done; 
    private CountDownLatch completion; 

    public producer(CountDownLatch completion) { 
     this.completion = completion; 
    } 

    void produce(food F) { 
     times = F.times; 
     f = F; 
     Thread t = new Thread(this); 
     t.start(); 
    } 


    public void run() { 
     while (this.times-- > 0) { 
      f.add(times); 
     } 
     completion.countDown(); 
    } 
} 

class consumer implements Runnable { 

    int times; 
    food f; 
    private CountDownLatch completion; 

    public consumer(CountDownLatch completion) { 
     this.completion = completion; 
    } 

    void consume(food F) { 
     times = F.times; 
     f = F; 
     Thread t = new Thread(this); 
     t.start(); 
    } 

    public void run() { 
     while (this.times-- > 0) { 
      f.get(); 
     } 
     completion.countDown(); 
    } 
}