3 Threads Printing numbers in sequence

Question

I am trying to write a simple code to print numbers in sequence. Scenario is like

Thread  Number
T1        1
T2        2
T3        3
T1        4
T2        5
T3          


        

Answer 1

Though this is a bad way for using threads, if we still want it a generic solution can be to have a worker thread which will store its id:

class Worker extends Thread {
    private final ResourceLock resourceLock;
    private final int threadNumber;
    private final AtomicInteger counter;
    private volatile boolean running = true;
    public Worker(ResourceLock resourceLock, int threadNumber, AtomicInteger counter) {
        this.resourceLock = resourceLock;
        this.threadNumber = threadNumber;
        this.counter = counter;
    }
    @Override
    public void run() {
        while (running) {
            try {
                synchronized (resourceLock) {
                    while (resourceLock.flag != threadNumber) {
                        resourceLock.wait();
                    }
                    System.out.println("Thread:" + threadNumber + " value: " + counter.incrementAndGet());
                    Thread.sleep(1000);
                    resourceLock.flag = (threadNumber + 1) % resourceLock.threadsCount;
                    resourceLock.notifyAll();
                }
            } catch (Exception e) {
                System.out.println("Exception: " + e);
            }
        }
    }
    public void shutdown() {
        running = false;
    }
}

The ResourceLock class would store flag and max threads count:

class ResourceLock {
    public volatile int flag;
    public final int threadsCount;

    public ResourceLock(int threadsCount) {
        this.flag = 0;
        this.threadsCount = threadsCount;
    }
}

And then main class can use it as below:

public static void main(String[] args) throws InterruptedException {
        final int threadsCount = 3;
        final ResourceLock lock = new ResourceLock(threadsCount);
        Worker[] threads = new Worker[threadsCount];
        final AtomicInteger counter = new AtomicInteger(0);
        for(int i=0; i

Here after a certain delay we may like to stop the count and the method shutdown in worker provides this provision.