ThreadSafeStack.java

package modern.challenge;

import java.util.Stack;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.logging.Logger;

public class ThreadSafeStack {

    private static final Logger logger = Logger.getLogger(ThreadSafeStack.class.getName());

    private static Stack<Integer> stack = new Stack<>();

    private static final Producer producer = new Producer();
    private static final Consumer consumer = new Consumer();
    private static ExecutorService producerService
            = Executors.newSingleThreadExecutor();
    private static ExecutorService consumerService
            = Executors.newSingleThreadExecutor();

    private static class Producer implements Runnable {

        @Override
        public void run() {
            while (true) {
                
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException ex) {
                    Thread.currentThread().interrupt();
                }
                
                int item = (int) (Math.random() * 1000);
                stack.push(item);
                logger.info(() -> "Produced: " + item
                        + " by " + Thread.currentThread().getName());
            }
        }
    }

    private static class Consumer implements Runnable {

        @Override
        public void run() {
            while (true) {

                try {
                    Thread.sleep(2000);
                } catch (InterruptedException ex) {
                    Thread.currentThread().interrupt();
                }

                int item = stack.pop();
                logger.info(() -> "Consumed: " + item
                        + " by " + Thread.currentThread().getName());
            }
        }
    }

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

        System.setProperty("java.util.logging.SimpleFormatter.format",
                "[%1$tT] [%4$-7s] %5$s %n");

        producerService.execute(producer);
        consumerService.execute(consumer);

        // since the producer and consumer run in a while(true) the application must be stopped manually
    }
}