Java 中 wait()、notify() 和 notifyAll() 方法的重要性?
javaobject oriented programmingprogramming更新于 2024/7/25 20:14:00
Java 中线程可以通过 wait()、notify() 和 notifyAll() 方法相互通信。这些是 Object 类中定义的 final 方法，只能在 synchronized 上下文中调用。wait() 方法使当前线程等待，直到另一个线程调用该对象的 notify() 或 notifyAll() 方法。notify() 方法唤醒正在等待该对象监视器的单个线程。 notifyAll() 方法唤醒所有等待该对象监视器的线程。线程通过调用 wait() 方法之一等待对象的监视器。如果当前线程不是对象监视器的所有者，这些方法可能会抛出 IllegalMonitorStateException 。
wait() 方法语法
public final void wait() 抛出 InterruptedException
notify() 方法语法
public final void notify()
NotifyAll() 方法语法
public final void notifyAll()
示例
public class WaitNotifyTest {
private static final long SLEEP_INTERVAL = 3000;
private boolean running = true;
private Thread thread;
public void start() {
print("Inside start() method");
thread = new Thread(new Runnable() {
@Override
public void run() {
print("Inside run() method");
try {
Thread.sleep(SLEEP_INTERVAL);
} catch(InterruptedException e) {
Thread.currentThread().interrupt();
}
synchronized(WaitNotifyTest.this) {
running = false;
WaitNotifyTest.this.notify();
}
}
});
thread.start();
}
public void join() throws InterruptedException {
print("Inside join() method");
synchronized(this) {
while(running) {
print("Waiting for the peer thread to finish.");
wait(); //waiting, not running
}
print("Peer thread finished.");
}
}
private void print(String s) {
System.out.println(s);
}
public static void main(String[] args) throws InterruptedException {
WaitNotifyTest test = new WaitNotifyTest();
test.start();
test.join();
}
}
输出
Inside start() method Inside join() method Waiting for the peer thread to finish. Inside run() method Peer thread finished.
