1114. Print in Order 

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class Foo {

    private final CountDownLatch latchA;
    private final CountDownLatch latchB;

    public Foo() {
        this.latchA = new CountDownLatch(1);
        this.latchB = new CountDownLatch(1);
    }

    public void first(Runnable printFirst) throws InterruptedException {
        printFirst.run();
        latchA.countDown();
    }

    public void second(Runnable printSecond) throws InterruptedException {
        latchA.await();
        printSecond.run();
        latchB.countDown();
    }

    public void third(Runnable printThird) throws InterruptedException {
        latchB.await();
        printThird.run();
    }

}
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class Foo {

    public Foo() {

    }

    private final Object lock = new Object();
    private boolean shouldPrintFirst = true;
    private boolean shouldPrintSecond = false;
    private boolean shouldPrintThird = false;

    public void first(Runnable printFirst) throws InterruptedException {
        synchronized (lock) {
            while (!shouldPrintFirst) {
                lock.wait();
            }
            printFirst.run();
            shouldPrintSecond = true;
            shouldPrintFirst = false;
            lock.notifyAll();
        }
    }

    public void second(Runnable printSecond) throws InterruptedException {
        synchronized (lock) {
            while (!shouldPrintSecond) {
                lock.wait();
            }
            printSecond.run();
            shouldPrintThird = true;
            shouldPrintSecond = false;
            lock.notifyAll();
        }
    }

    public void third(Runnable printThird) throws InterruptedException {
        synchronized (lock) {
            while (!shouldPrintThird) {
                lock.wait();
            }
            printThird.run();
            shouldPrintFirst = true;
            shouldPrintThird = false;
            lock.notifyAll();
        }
    }

}

References

1114. Print in Order