1. Java线程的状态包括：
NEW、READY、RUNNING、WAITING、TIMED_WAITING、BLOCKED
2. WAITING、TIMED_WAITING与BLOCKED的区别：
（1）WAITING：进入等待状态，方式：wait/join/park方法进入无限等待，通过notify/notifyAll/unpark唤醒；
（2）TIMED_WAITING：与WAITING类似，方式：a. 给定等待时间的wait/join/park方法；b. sleep方法；
（3）BLOCKED：被动进入等待状态，方式：进入Synchronized块；
私以为官方的才是最靠谱的，以下为来自jdk1.8：java.lang.Thread.state的注释：
/**
* Thread state for a thread which has not yet started.
*/
NEW,
/**
* Thread state for a runnable thread. A thread in the runnable
* state is executing in the Java virtual machine but it may
* be waiting for other resources from the operating system
* such as processor.
*/
RUNNABLE,
/**
* Thread state for a thread blocked waiting for a monitor lock.
* A thread in the blocked state is waiting for a monitor lock
* to enter a synchronized block/method or
* reenter a synchronized block/method after calling
* {@link Object#wait() Object.wait}.
*/
BLOCKED,
/**
* Thread state for a waiting thread.
* A thread is in the waiting state due to calling one of the
* following methods:
* <ul>
* <li>{@link Object#wait() Object.wait} with no timeout</li>
* <li>{@link #join() Thread.join} with no timeout</li>
* <li>{@link LockSupport#park() LockSupport.park}</li>
* </ul>
*
* <p>A thread in the waiting state is waiting for another thread to
* perform a particular action.
*
* For example, a thread that has called <tt>Object.wait()</tt>
* on an object is waiting for another thread to call
* <tt>Object.notify()</tt> or <tt>Object.notifyAll()</tt> on
* that object. A thread that has called <tt>Thread.join()</tt>
* is waiting for a specified thread to terminate.
*/
WAITING,
/**
* Thread state for a waiting thread with a specified waiting time.
* A thread is in the timed waiting state due to calling one of
* the following methods with a specified positive waiting time:
* <ul>
* <li>{@link #sleep Thread.sleep}</li>
* <li>{@link Object#wait(long) Object.wait} with timeout</li>
* <li>{@link #join(long) Thread.join} with timeout</li>
* <li>{@link LockSupport#parkNanos LockSupport.parkNanos}</li>
* <li>{@link LockSupport#parkUntil LockSupport.parkUntil}</li>
* </ul>
*/
TIMED_WAITING,
/**
* Thread state for a terminated thread.
* The thread has completed execution.
*/
TERMINATED;
3. Object.wait()和Thread.sleep()
（1）Object.wait()会释放锁，等到唤醒条件满足之后，线程进入锁池，获取锁之后进入READY；Thread.sleep()不会释放锁；
（2）wait()与wait(0)同义，无限等待；sleep(0)的意思是不等待。
4. wait()需要先获取对象的monitor锁，才能调用，否则报出异常java.lang.IllegalMonitorStateException，常用写法：
synchronized(obj){
try {
obj.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}