在给定线程ID的情况下在特定线程上运行方法

Question

如果我知道特定的线程ID。如何做到以下几点？

主题。 getThreadById（id）.continueWork（）;

可能吗？

public class Test implements Runnable { 

public void run() { 
    while(true){ 
    pause(); 

    doSomework(); 
    } 
} 

private void doSomework() { 
    System.out.println("do some work"); 
} 

public synchronized void pause() { 
    if (Tester.waitCondition == true) { 
     try { 
      wait(); 
     } catch (InterruptedException e) { 
      e.printStackTrace(); 
     } 
    } 
} 

public synchronized void continueWork() { 
    notify(); 
} 
} 

public class Tester { 

public static boolean waitCondition = true; 

public static void main(String[] args) { 
    Thread nThread = new Thread(new Test()); 
    nThread.start(); 
    waitCondition = false; 
    Thread nThread1 = new Thread(new Test()); 
    nThread1.start(); 
    Thread nThread2 = new Thread(new Test()); 
    nThread2.start(); 
    Thread nThread3 = new Thread(new Test()); 
    nThread3.start(); 

    Long id = nThread.getId(); 
    Thread.getThreadById(id).continueWork(); 


} 
} 

Answer 1

诠：

public class Tester { 
    // Apologies, I'm too lazy to create two separate files 
    static public class Test implements Runnable { 

    private void doSomework() { 
     System.out.print(
      "do some work on Thread: " 
     +Thread.currentThread().getId() 
    ); 
     try { 
     Thread.sleep(500); // just to simulate a load 
     } 
     catch(InterruptedException e) { 
     // ignore 
     } 
    } 

    public void run() { 
     do { 
     boolean shouldIWait=true; 
     synchronized(Tester.lockingObj) { 
      Boolean flag=Tester.waitConditions.get(Thread.currentThread().getId()); 
      if(null!=flag) { 
      shouldIWait=flag.booleanValue(); 
      } // if null, the tester started me before creating my flag. I'll wait 
      if(shouldIWait) { 
      // I need to wait for someone to wake me 
      try { 
       Tester.lockingObj.wait(); 
      } catch (InterruptedException e) { 
       e.printStackTrace(); 
       // well, I'm interrupted, so I'll do no more work. 
       break; 
      } 
      } 
     } 
     if(false==shouldIWait) { 
      // waiting no more 
      this.doSomework(); 
     } 
     } while(true); 
    } 

    } 

    public static Object lockingObj=new Object(); 

    public static TreeMap<Long, Boolean> waitConditions= 
     new TreeMap<Long, Boolean>(); 

    public static void main(String[] args) { 
    Thread nThread = new Thread(new Test()); 
    Thread nThread1 = new Thread(new Test()); 
    Thread nThread2 = new Thread(new Test()); 
    Thread nThread3 = new Thread(new Test()); 

    // when starting, all threads will be waiting 
    waitConditions.put(nThread.getId(), true); 
    waitConditions.put(nThread.getId(), true); 
    waitConditions.put(nThread.getId(), true); 
    waitConditions.put(nThread.getId(), true); 

    nThread2.start(); 
    nThread1.start(); 
    nThread.start(); 
    nThread3.start(); 

    Long id = nThread.getId(); 
    synchronized (lockingObj) { // when notified, all thread should wakeup 
     waitConditions.put(id, false); // but only nThread will be allowed to doSomeWork 
     lockingObj.notifyAll(); // wake up all the threads. 
           // Those not allowed, will go into 
           // back waiting 
    } 

    try { 
     // just to have the main thread still running for a while 
     Thread.sleep(3000); 
    } catch (InterruptedException e) { 
    } 
    // maybe we want to switch of nThread and start another? 
    synchronized (lockingObj) { 
     waitConditions.put(id, true); 
     waitConditions.put(nThread1.getId(), false); 
     lockingObj.notifyAll(); 
    } 
    try { 
     // just to have the main thread still running for a while 
     Thread.sleep(3000); 
    } catch (InterruptedException e) { 
    } 

    } 
} 

Answer 2

您需要使用锁来阻塞线程，然后调用锁的notify方法来设置阻塞的线程可运行。
如果不止一个线程要继续，您将需要Condition。
像打击：

final Lock lock = new ReentrantLock(); 

final Condition condition1 = lock.newCondition(); 
final Condition condition2 = lock.newCondition(); 

Thread t = new Thread() { 
    @Override 
    public void run() { 

    try { 
     lock.lock(); 
     condition1.await(); 
     System.out.println("end cdt1"); 
    } catch (InterruptedException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } finally { 
     lock.unlock(); 
    } 
    } 
}; 

t.start(); 

Thread t1 = new Thread() { 
    @Override 
    public void run() { 

    try { 
     lock.lock(); 
     condition2.await(); 
     System.out.println("end cdt2"); 
    } catch (InterruptedException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } finally { 
     lock.unlock(); 
    } 

    } 
}; 
t1.start(); 

Thread.sleep(1000); 

Thread tt = new Thread() { 
    @Override 
    public void run() { 
    try { 
     lock.lock(); 
     condition1.signal(); 
    } catch (Exception e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } finally { 
     lock.unlock(); 
    } 
    } 
}; 
tt.start(); 

Thread.sleep(2000); 

Thread tt1 = new Thread() { 
    @Override 
    public void run() { 
    try { 
     lock.lock(); 
     condition2.signal(); 
    } catch (Exception e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } finally { 
     lock.unlock(); 
    } 
    } 
}; 
tt1.start();