Condition接口的await()、signal()

Condition是在java 1.5中才出现的，它用来替代传统的Object的wait()、notify()实现线程间的协作，相比使用Object的wait()、notify()，使用Condition1的await()、signal()这种方式实现线程间协作更加安全和高效。因此通常来说比较推荐使用Condition，阻塞队列实际上是使用了Condition来模拟线程间协作。

Condition是个接口，基本的方法就是await()和signal()方法；

Condition的创建：
Condition依赖于Lock接口，生成一个Condition的基本代码是lock.newCondition()

调用Condition的await()、signal()、signalAll()方法，都必须在lock保护之内，就是说必须在lock.lock()和lock.unlock之间才可以使用

 

Condition condition = lock.newCondition();
condition.await();  类似wait
Condition. Signal() 类似notify

 

 

例子：

class Res {
 public String userName;
 public String sex;
 public boolean flag = false;
 Lock lock = new ReentrantLock();
}

 

class InputThread extends Thread {


 private Res res;
 Condition newCondition;


 public InputThread(Res res, Condition newCondition) {
  this.res = res;
  this.newCondition=newCondition;
 }

 

 @Override
 public void run() {
  int count = 0;
  while (true) {
   // synchronized (res) {

   try {
    res.lock.lock();
    if (res.flag) {
     try {
//      res.wait();
      newCondition.await();
     } catch (Exception e) {
      // TODO: handle exception
     }
    }
    if (count == 0) {
     res.userName = "小强";
     res.sex = "男";
    } else {
     res.userName = "小红";
     res.sex = "女";
    }
    count = (count + 1) % 2;
    res.flag = true;
//    res.notify();
    newCondition.signal();
   } catch (Exception e) {
    // TODO: handle exception
   }finally {
    res.lock.unlock();
   }
  }

  // }
 }
}

class OutThrad extends Thread {
 private Res res;
 private Condition newCondition;


 public OutThrad(Res res,Condition newCondition) {
       this.res = res;
       this.newCondition=newCondition;
 }

 

 @Override
 public void run() {
  while (true) {
//   synchronized (res) {
   try {
    res.lock.lock();
    if (!res.flag) {
     try {
//      res.wait();
      newCondition.await();
     } catch (Exception e) {
      // TODO: handle exception
     }
    }
    System.out.println(res.userName + "," + res.sex);
    res.flag = false;
//    res.notify();
    newCondition.signal();
   } catch (Exception e) {
    // TODO: handle exception
   }finally {
    res.lock.unlock();
   }
//   }
  }

 }
}

public class ThreadDemo01 {

 public static void main(String[] args) {
  Res res = new Res();
  Condition newCondition = res.lock.newCondition();
  InputThread inputThread = new InputThread(res,newCondition);
  OutThrad outThrad = new OutThrad(res,newCondition);
  inputThread.start();
  outThrad.start();
 }

}