两种方式实现线程交替打印

package deadLock;
/**
 * @author zhy
 * @create 2021/9/30 23:41
 */
public class Test4 {
    static boolean flag = true;
    public static void main(String[] args) {
        new Thread(() -> {
            synchronized (Test4.class) {
                for (int i = 0; i < 100; i += 2) {
                    while (!flag) {
                        try {
                            Test4.class.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    System.out.println(Thread.currentThread().getName() + " : " + i);
                    flag = false;
                    Test4.class.notifyAll();
                }
            }
        }, "t1").start();
        new Thread(() -> {
            synchronized (Test4.class) {
                for (int i = 1; i < 100; i += 2) {
                    while (flag) {
                        try {
                            Test4.class.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    System.out.println(Thread.currentThread().getName() + " : " + i);
                    flag = true;
                    Test4.class.notifyAll();
                }
            }
        }, "t2").start();
    }
}

package deadLock;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
 * @author zhy
 * @create 2021/9/30 23:21
 */
public class Test3 {
    static Lock lock = new ReentrantLock();
    static Condition condition1 = lock.newCondition();
    static Condition condition2 = lock.newCondition();
    static boolean flag = true;
    public static void main(String[] args) {
        new Thread(() -> {
            for (int i = 0; i < 100; i += 2) {
                try {
                    lock.lock();
                    while (!flag){
                        condition1.await();
                    }
                    System.out.println(Thread.currentThread().getName() + ":" + i);
                    flag = false;
                    condition2.signal();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } finally {
                    lock.unlock();
                }
            }
        }, "t1").start();
        new Thread(() -> {
            for (int i = 1; i < 100; i += 2) {
                try {
                    lock.lock();
                    while (flag){
                        condition2.await();
                    }
                    System.out.println(Thread.currentThread().getName() + ":" + i);
                    flag = true;
                    condition1.signal();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } finally {
                    lock.unlock();
                }
            }
        }, "t2").start();
    }
}