如何让两个线程“系鞋带"

前两天转了马士兵老师的《没错，我就是厕所所长！》，正好有朋友和我讨论一个线程打印的问题，于是今天就趁着周末们睡觉，写了个简单的实现。

题干，是这样的，通过2个线程，交替输出 A1B2C3....Z26

先贴出我的实现，欢迎大家和我讨论

public class TwoThread2 {
    public static class Printer{
        public synchronized void print(String i) {
            try {
                this.notify();
                System.out.println(Thread.currentThread().getName() + " " + i);
                this.wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    //两个线程交替输出， A1B2C3.....Z26
    public static final int SETPS = 26;
    public static class ThreadNum extends Thread {
        private int startCharCount = 1;
        private Printer p = new Printer();
        public Printer getP() {
            return p;
        }
        public void setP(Printer p) {
            this.p = p;
        }
        @Override
        public void run() {
            for (int i = 0; i < SETPS; i++) {
                p.print(startCharCount+++"");
            }
        }
    }
    public static class ThreadStr extends Thread {
        private int startCharCount = 65;
        private Printer p = new Printer();
        public Printer getP() {
            return p;
        }
        public void setP(Printer p) {
            this.p = p;
        }
        @Override
        public void run() {
            for (int i = 0; i < SETPS; i++) {
                p.print( (char) startCharCount+++"");
            }
        }
    }
    public static void main(String[] args) {
        Printer p = new Printer();
        ThreadNum tn = new ThreadNum();
        tn.setName("Thread num :");
        tn.setP(p);
        ThreadStr ts = new ThreadStr();
        ts.setName("Thread str :");
        ts.setP(p);
        ts.start();
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        tn.start();
    }
}

大概实现就是这样的，这个流程有点想系鞋带，用一个线程专门打印字符串，一个线程打印数字，然后线程交替加锁，释放，流程大概如下所示。

如果文章对您有那么一点点帮助，我将倍感荣幸，