Java Volatile Keyword

VolatileTest.java

public class VolatileTest {

  private static final int MAX_TASK_COUNT = 5;

  private static volatile int tasks = 0;

  public static void main(String[] args) {
    new Employee().start();
    new Manager().start();
  }

  static class Employee extends Thread {
    @Override
    public void run() {
      int local_value = tasks;
      while (local_value < MAX_TASK_COUNT) {
        if (local_value != tasks) {
          System.out.println("Got Change for tasks : " + tasks);
          local_value = tasks;
        }
      }
    }
  }

  static class Manager extends Thread {
    @Override
    public void run() {
      int local_value = tasks;
      while (tasks < MAX_TASK_COUNT) {
        System.out.println("Incrementing tasks to " + (local_value + 1));
        tasks = ++local_value;
        try {
          Thread.sleep(500);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
      }
    }
  }
}