Java多线程之线程状态的迁移详解

public class ThreadState {
    static Object lock = new Object();
    
    // 模拟 NEW、RUNNABLE、WAITING、TIMED_WAITING、BLOCKED、TERMINATED
    public static void main(String[] args) {
        ThreadState thisObj = new ThreadState();
        Thread t1 = new Thread(() -> {
            try {
                // 先获取 t2 对象
                Thread t2 = getThreadByName("t2");
                // 先执行一套逻辑，推迟同步代码块的调用
                String str = "";
                for (int i = 0; i < 10000; i++) {
                    str += i;
                }
                // 调用同步代码块
                thisObj.doSync();
                // t2准备插队
                t2.join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }, "t1");
        System.out.println("t1 刚创建：" + t1.getState());
        
        Thread t2 = new Thread(() -> {
            try {
                // 直接获取同步锁
                thisObj.doSync();
                // 释放锁后在运行一段时间
                TimeUnit.SECONDS.sleep(30);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }, "t2");
        
        Thread monitor = new Thread(() -> {
            Thread.State t1State = null;
            while (true) {
                if (!t1.getState().equals(t1State)) {
                    t1State = t1.getState();
                    System.out.println("t1 此刻状态：" + t1.getState());
                }
                if (t1State.equals(Thread.State.TERMINATED))
                    break;
            }
        }, "monitor");
        
        monitor.start();
        t2.start();
        t1.start();
    }
    
    public synchronized void doSync() {
        try {
            TimeUnit.SECONDS.sleep(1);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        String str = "";
        for (int i = 0; i < 100000; i++) {
            str += i;
        }
    }
    
    public static Thread getThreadByName(String name) {
        Optional<Thread> first = Thread.getAllStackTraces()
                .keySet()
                .stream()
                .filter(thread -> thread.getName().equals(name))
                .findFirst();
        return first.get();
    }
}