TWS.java

//monitors
//EB6, Q4
//E = W < S
import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.locks.Condition;
public class TWS implements Runnable{
    private int state = 1;
    private Condition first = new ReentrantLock().newCondition();
    private Condition second = new ReentrantLock().newCondition();
    private Condition third = new ReentrantLock().newCondition();
    public synchronized void first() throws InterruptedException{
        while(state != 1)
            first.wait();
        System.out.println("first");
        state = 2;
        second.signal();
    }

    public synchronized void second() throws InterruptedException{
        while(state != 2)
            second.wait();
        System.out.println("second");
        state = 3;
        third.signal();
    }

    public synchronized void third() throws InterruptedException{
        while(state != 3)
            third.wait();
        System.out.println("third");
        state = 1;
        first.signal();
    }

    public void run(){
        Thread t = new Thread(new TWS());
        t.start();
        try{
            t.join();
        } catch(Exception e){
            e.printStackTrace();
        }
    }

    public static void main(String[] args) throws InterruptedException{

    }
}