1、wait的用法

/** * Causes the current thread to wait until another thread invokes the * {@link java.lang.Object#notify()} method or the * {@link java.lang.Object#notifyAll()} method for this object. * In other words, this method behaves exactly as if it simply * performs the call {@code wait(0)}. * <p> * The current thread must own this object's monitor. The thread * releases ownership of this monitor and waits until another thread * notifies threads waiting on this object's monitor to wake up * either through a call to the {@code notify} method or the * {@code notifyAll} method. The thread then waits until it can * re-obtain ownership of the monitor and resumes execution. * <p> * As in the one argument version, interrupts and spurious wakeups are * possible, and this method should always be used in a loop: * <pre> *     synchronized (obj) { *         while (&lt;condition does not hold&gt;) *             obj.wait(); *         ... // Perform action appropriate to condition *     } * </pre> * This method should only be called by a thread that is the owner * of this object's monitor. See the {@code notify} method for a * description of the ways in which a thread can become the owner of * a monitor. * * @throws IllegalMonitorStateException  if the current thread is not *               the owner of the object's monitor. * @throws InterruptedException if any thread interrupted the *             current thread before or while the current thread *             was waiting for a notification.  The <i>interrupted *             status</i> of the current thread is cleared when *             this exception is thrown. * @see java.lang.Object#notify() * @see java.lang.Object#notifyAll() */ public final void wait() throws InterruptedException {    wait(0);}
  • 参考wait的注解， 当调用wait的时候必须要持有监视器锁，不然会跑出非法监视器异样


为什么wait()和notify()须要搭配synchonized关键字应用

2 sleep

/** * Causes the currently executing thread to sleep (temporarily cease * execution) for the specified number of milliseconds, subject to * the precision and accuracy of system timers and schedulers. The thread * does not lose ownership of any monitors. * * @param millis *         the length of time to sleep in milliseconds * * @throws IllegalArgumentException *          if the value of {@code millis} is negative * * @throws InterruptedException *          if any thread has interrupted the current thread. The * <i>interrupted status</i> of the current thread is *          cleared when this exception is thrown.  */ public static native void sleep(long millis) throws InterruptedException;