1、Object提供的等待通知方法
public class MainTest {
private static volatile int condition = 0;
private static final Object object = new Object();
public static void main(String[] args) throws InterruptedException {
Thread thread = new Thread(new Runnable() {
@Override
public void run() {
synchronized (object) {
while (condition != 1) {
try {
object.wait();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
System.out.println("线程执行完毕");
}
}
});
thread.start();
Thread.sleep(2000);
condition = 1;
synchronized (object) {
object.notify();
}
}
}
2、显示锁提供的等待通知
public class MainTest {
private static volatile int condition = 0;
private static ReentrantLock reentrantLock = new ReentrantLock();
private static Condition lockCondition = reentrantLock.newCondition();
public static void main(String[] args) {
Thread thread = new Thread(new Runnable() {
@Override
public void run() {
reentrantLock.lock();
try {
while (condition != 1) {
//lockCondition.wait();//不是下面这个玩意
//必须要获取到锁，不然报错；
//和对象的wait()必须在同步块中使用一个道理
lockCondition.await();
}
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
reentrantLock.unlock();
}
System.out.println("线程执行完毕");
}
});
thread.start();
condition = 1;
reentrantLock.lock();
try {
Thread.sleep(2000);
lockCondition.signal();
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
reentrantLock.unlock();
}
}
}
3、区别
lock.newCondition() 获取多个Condition对象。
在一个lock对象上，可以有多个等待队列。
而Object的等待通知只有一个等待队列。
4、源码
Condition.await()会构造一个新的等待队列节点加入到等待队列队尾。
Condition.signal()会通知等待队列队首的节点，将节点加入同步队列。
见源码
