Java多线程：用三个线程控制循环输出10次ABC

这个是昨日面试时的一个题目，考查的是线程同步与协调处理相关的知识。但当时的我是在线写的，但后来发现完全错了。之前自我感觉对多线程已经掌握的很OK了，结果当时全懵了。哈哈，只是当时已惘然。
现在参考这篇文章：https://yq.aliyun.com/articles/34834
自己再写个类似的，以加深认识吧。
public class PrintABC {

public static void main(String[] args) {
    Print print = new Print();
    Thread thread_a = new Thread(new PrintThread(print, 'A'));
    Thread thread_b = new Thread(new PrintThread(print, 'B'));
    Thread thread_c = new Thread(new PrintThread(print, 'C'));
    thread_a.start();
    thread_b.start();
    thread_c.start();
}

}

class PrintThread implements Runnable {

//打印机只有一台
private Print print;
//设置默认值[即第一个打印值]和下一个的打印值
private static volatile char next='A';
private char val;

public PrintThread(Print print, char val) {
    this.print = print;
    this.val = val;
}

public void run() {
    try {
        for (int i = 0; i < 10; ) {
            synchronized (print) {
                //协调线程顺序打印ABCABC
                if(val=='A'&&next==val) {
                    print.print(val);
                    next='B';
                    i++;
                }
                if(val=='B'&&next==val) {
                    print.print(val);
                    next='C';
                    i++;
                }
                if(val=='C'&&next==val) {
                    print.print(val);
                    next='A';
                    i++;
                }
            }
        }
    } catch (Exception ex) {
        ex.printStackTrace();
    }
}

}

class Print {

//private char next;
public void print(char val) throws Exception {
    System.out.print(val);
}

}
结果为：ABCABCABCABCABCABCABCABCABCABC