java 线程状态

Thread类内的State枚举描述了线程的状态：

public enum State {
    NEW, // 线程还没有启动
    RUNNABLE, // 正在运行
    BLOCKED, // 等待监视器锁。在同步代码块外面阻塞住了
    WAITING, // 等待Object.notify()，调用Object.wait()后的状态
    TIMED_WAITING, //调用Object.wait(1000)或者Thread.sleep(1000)后的状态
    TERMINATED; //结束
}

代码示例打印线程状态：

public static void main(String[] args) {
    final Object obj = new Object();
    
    Thread thread = new Thread(new Runnable() {
        @Override
        public void run() {
            synchronized(obj) {
                System.out.println(Thread.currentThread().getName());
                try {
                    // TIMED_WAITING
                    // Thread.sleep(5000);
                    
                    // WAITING
                    obj.wait();
                } catch (InterruptedException e) {}
                
            }
        }
    });

    Thread thread2 = new Thread(new Runnable() {
        @Override
        public void run() {
            //线程阻塞在synchronized代码块外，为blocked
            synchronized(obj) {
                System.out.println(Thread.currentThread().getName());
                try {
                    // TIMED_WAITING
                    obj.wait(1000);
                } catch (InterruptedException e) {}
                
            }
        }
    });
    
    thread.start();
    thread2.start();
    
    try {
        Thread.sleep(500);
    } catch (InterruptedException e) {}
    System.out.println(thread.getName() + "," + thread.getState());
    System.out.println(thread2.getName() + "," + thread2.getState());
}