两个线程，一个线程打印1~52，另一个线程打印字母A-Z，打印顺序为12A34B56C……5152Z

使用wait,notify实现

public class Test {
    public synchronized void a() {
        for (int i = 1; i <= 52; i++) {
            System.out.print(i);
            if (i % 2 == 0) {
                notify();
                try {
                    wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    public synchronized void b() {
        for (char i = 'A'; i <= 'Z'; i++) {
            System.out.print(i);
            notify();
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

    }

    public static void main(String[] args) {
        Test test = new Test();
        new Thread(test::a).start();
        new Thread(test::b).start();
    }
}

使用condition实现

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class T {

    Lock lock = new ReentrantLock();
    Condition aa = lock.newCondition();
    Condition bb = lock.newCondition();

    public void a() {
        lock.lock();
        try {
            for (int i = 1; i <= 52; i++) {
                System.out.print(i);
                if (i % 2 == 0) {
                    bb.signalAll();
                    try {
                        aa.await();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        } finally {
            lock.unlock();
        }
    }

    public void b() {
        lock.lock();
        try {
            for (char i = 'A'; i <= 'Z'; i++) {
                System.out.print(i);
                aa.signalAll();
                try {
                    bb.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        } finally {
            lock.unlock();
        }
    }

    public static void main(String[] args) {
        T t = new T();
        new Thread(t::a).start();
        new Thread(t::b).start();
    }
}