三个线程按循序一个打印A一个打印B一个打印C 循环打印？

第一种

public static volatile int flag = 1;
public static void printABC1(){
    Thread t1 = new Thread(() -> {
        while (true) {
            synchronized (obj1) {
                while (flag != 1){
                    try {
                        obj1.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                try {
                    System.out.println("T1:A");
                    Thread.sleep(1000);
                    flag = 2;
                    obj1.notifyAll();
                    obj1.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    });
    Thread t2 = new Thread(() -> {
        while (true) {
            synchronized (obj1) {
                while (flag != 2){
                    try {
                        obj1.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                try {
                    System.out.println("T2:B");
                    Thread.sleep(1000);
                    flag = 3;
                    obj1.notifyAll();
                    obj1.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    });
    Thread t3 = new Thread(() -> {
        while (true) {
            synchronized (obj1) {
                while (flag != 3){
                    try {
                        obj1.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                try {
                    System.out.println("T3:C");
                    Thread.sleep(1000);
                    flag = 1;
                    obj1.notifyAll();
                    obj1.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    });
    t1.start();
    t2.start();
    t3.start();
}

第二种

public static ReentrantLock lock = new ReentrantLock();
public static Condition condition1 = lock.newCondition();
public static volatile int flag2 = 0;
public static void printABC2(){
    Thread t1 = new Thread(() -> {
        while (true){
            lock.lock();
            while (flag2 % 3 != 0){
                try {
                    condition1.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            try {
                System.out.println("T1:A");
                Thread.sleep(1000);
                flag2++;
                condition1.signalAll();
                condition1.await();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }finally {
                lock.unlock();
            }
        }
    });
    Thread t2 = new Thread(() -> {
        while (true) {
            lock.lock();
            while (flag2 % 3 != 1){
                try {
                    condition1.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            try {
                System.out.println("T2:B");
                Thread.sleep(1000);
                flag2++;
                condition1.signalAll();
                condition1.await();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }finally {
                lock.unlock();
            }
        }
    });
    Thread t3 = new Thread(() -> {
        while (true) {
            lock.lock();
            while (flag2 % 3 != 2){
                try {
                    condition1.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            try {
                System.out.println("T3:C");
                Thread.sleep(1000);
                flag2++;
                condition1.signalAll();
                condition1.await();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }finally {
                lock.unlock();
            }
        }
    });
    t1.start();
    t2.start();
    t3.start();
}