gistfile1.txt

public class SynchronizationTests {

    @Test
    public void testMultipleIncrementers() throws InterruptedException {
        SimpleLongCounter counter = new SimpleLongCounter();

        List<SimpleIncrementer> simpleIncrementerList = new ArrayList<SimpleIncrementer>();

        for(int i = 0; i < 3; i++) {
            simpleIncrementerList.add(new SimpleIncrementer(counter));
        }

        for(SimpleIncrementer incrementer : simpleIncrementerList) {
            incrementer.start();
        }

        Thread.sleep(1000);
        for(SimpleIncrementer incrementer : simpleIncrementerList) {
            incrementer.stopIncrementing();
        }

        for(SimpleIncrementer incrementer : simpleIncrementerList) {
            incrementer.join();
        }

        long countTillNow = 0;
        for(SimpleIncrementer incrementer : simpleIncrementerList) {
            countTillNow += incrementer.count();
        }

        System.out.println(countTillNow);
        System.out.println(counter.count());
        Assert.assertEquals(true, countTillNow == counter.count());
    }

    private class SimpleLongCounter {
        private long count = 0;

        public long count() {

            return count;
        }

        public void increment() {
            count++;
        }
    }

    private class SimpleIncrementer extends Thread {
        private long trackCount = 0;
        private final SimpleLongCounter counter;
        private volatile boolean stopProcessing = false;

        public SimpleIncrementer(SimpleLongCounter counter) {
            this.counter = counter;
        }

        public long count() {
            return trackCount;
        }

        @Override
        public void run() {
            while(!stopProcessing) {
                trackCount++;
                counter.increment();
            }
        }

        public void stopIncrementing() {
            stopProcessing = true;
        }
    }
}