PrintInOrder.java

import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.ReentrantLock;

/**
 * 1114. Print In Order
 * @author LBW
 */
public class PrintInOrder {
    private AtomicInteger i = new AtomicInteger(0);


    public PrintInOrder() {
    }

    public void first(Runnable printFirst) throws InterruptedException {

        // printFirst.run() outputs "first". Do not change or remove this line.
        printFirst.run();
        i.incrementAndGet();
    }

    public void second(Runnable printSecond) throws InterruptedException {

        // printSecond.run() outputs "second". Do not change or remove this line.
        while (i.get() != 1);
        printSecond.run();
        i.incrementAndGet();
    }

    public void third(Runnable printThird) throws InterruptedException {

        // printThird.run() outputs "third". Do not change or remove this line.
        while (i.get() != 2);
        printThird.run();
    }
}