/*功能：三个线程，一个打印A，一个打印B，一个打印C，主函数实现循环打印ABCABCABCABC...  共打印10次ABC*/

public class ThreadABC {
    public static void main(String[] args) {
        Print p = new Print();
        
        /*打印A的进程*/
        new Thread(new Runnable() {
            public void run() {
                for(int i = 0;i <10;++i){//我设置的i打印10次啊
                    p.print_A();
        /*为什么只打印 5 次？？？！！！*/
        /*加上下面这行代码，就能正常打印10次，why？？？*/
                    //try{Thread.sleep();}catch(Exception e){;}
                }
                
            }
        }).start();
        
        /*启动打印B的线程*/
        new Thread(new Runnable() {
            public void run() {
                while(true)
                p.print_B();
            }
        }).start();
        
        /*启动打印C的线程*/
        new Thread(new Runnable() {
            public void run() {
                while(true)
                p.print_C();
            }
        }).start();
    }
}

/**/
class Print {
    /*flag用来同步*/
    private int flag = 1;
    /*打印 A */
    synchronized void print_A() {
        
        if(flag == 1) {
            System.out.print("A");
            flag = 2;
            try {this.notifyAll();}catch(Exception e) {e.printStackTrace();}
        }
        else {
            try {this.wait();}catch(Exception e) {e.printStackTrace();}
        }
    }
    /*打印B*/
    synchronized void print_B() {
        if(flag == 2) {
            System.out.print("B");
            flag = 3;
            try {this.notifyAll();}catch(Exception e) {e.printStackTrace();}
        }
        else {
            try {this.wait();}catch(Exception e) {e.printStackTrace();}
        }
    }
    /*打印C*/
        synchronized void print_C() {
        if(flag == 3) {
            System.out.println("C");
            flag = 1;
            try {this.notifyAll();}catch(Exception e) {e.printStackTrace();}
        }
        else {
            try {this.wait();}catch(Exception e) {e.printStackTrace();}
        }
    }
}