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

public class TestSequential01{
    private static Lock lock = new ReentrantLock ();
    private static Condition[] conditions = {lock.newCondition (),lock.newCondition (),lock.newCondition ()};
    private volatile int state = 1;

    private void run(final int self) {
        int next = self % 3 + 1;
        while (true) {
            lock.lock ();
            try {
                while (this.state != self) {
                    conditions[self - 1].await ();
                }
                System.out.println (self);
                this.state = next;
                conditions[next - 1].signal ();
            } catch (InterruptedException e) {
                e.printStackTrace ();
            }
            lock.unlock ();
        }
    }

    public static void main(String[] args) {
        TestSequential01 rlc = new TestSequential01 ();
        for (int i = 1;i < 4;i++) {
            int j = i;
            new Thread (() -> rlc.run (j)).start ();
        }
    }
}