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

/**
 * 面试题  ---- 线程按序交替
 */
public class TestABCAlternate {

    public static void main(String[] args) {

        final AlternateDemo alternateDemo=new AlternateDemo();

        new  Thread(new Runnable(){
            public void run() {
                for (int i = 0; i < 20; i++) {
                    alternateDemo.loopA(i);
                }

            }           
        },"A").start();

        new  Thread(new Runnable(){
            public void run() {
                for (int i = 0; i < 20; i++) {
                    alternateDemo.loopB(i);
                }
            }           
        },"B").start();

        new  Thread(new Runnable(){
            public void run() {
                for (int i = 0; i < 20; i++) {
                    alternateDemo.loopC(i);
                    System.out.println("-----------------------");
                }
            }           
        },"C").start();

    }
}


class AlternateDemo{

    private int number=1;

    private Lock lock=new ReentrantLock();

    Condition condition1=lock.newCondition();
    Condition condition2=lock.newCondition();
    Condition condition3=lock.newCondition();

    public void loopA(int total){
        lock.lock();
        try{
            if(number!=1){
                condition1.await();
            }
            for (int i = 1; i <= 3; i++) {
                System.out.println(Thread.currentThread().getName()+" \t"+i+"\t"+total);
            }
            number=2;
            condition2.signal();

        }catch(Exception e){
            e.printStackTrace();
        }finally{
            lock.unlock();
        }
    }

    public void loopB(int total){
        lock.lock();
        try{
            if(number!=2){
                condition2.await();
            }
            for (int i = 1; i <= 4; i++) {
                System.out.println(Thread.currentThread().getName()+" \t"+i+"\t"+total);
            }
            number=3;
            condition3.signal();

        }catch(Exception e){
            e.printStackTrace();
        }finally{
            lock.unlock();
        }
    }

    public void loopC(int total){
        lock.lock();
        try{
            if(number!=3){
                condition3.await();
            }
            for (int i = 1; i <= 5; i++) {
                System.out.println(Thread.currentThread().getName()+" \t"+i+"\t"+total);
            }
            number=1;
            condition1.signal();

        }catch(Exception e){
            e.printStackTrace();
        }finally{
            lock.unlock();
        }
    }

}