[Scheduler Pattern] (Add) scheduler pattern #76

[tiennm99]

I just implemented common and easy to understand disciplines: First Come First Served, Priority scheduling, Shortest remaining time first, Round-robin scheduling. It would be great if someone were generous enough to implement more complicated disciplines.

[tiennm99]

CheckStyle stricts too many things, I think it's inconvenient

[tiennm99]

Sorry but I think I can't improve my code to fit CheckStyle. Maybe it will be good for professional, but not for me.
Because we want a simple demo Application, I write something like this:

public class Main {
  public static void main(String[] args) {
    Map<Integer, List<Task>> tasks = new HashMap<>();
    tasks.put(0, List.of(new Task(1, 3), new Task(2, 2), new Task(3, 4)));

    TaskScheduler scheduler = new FirstComeFirstServedScheduler();
    Simulator simulator = new Simulator(scheduler, tasks, 1, 100);
    simulator.simulate();
  }
}

Then CheckStyle blocks me with these errors:

[ERROR] src\main\java\com\iluwatar\scheduler\Main.java:[7,1] (design) HideUtilityClassConstructor: Utility classes should not have a public or default constructor.
[ERROR] src\main\java\com\iluwatar\scheduler\Main.java:[8,3] (javadoc) MissingJavadocMethod: Missing a Javadoc comment.
[ERROR] src\main\java\com\iluwatar\scheduler\Main.java:[8,27] (misc) FinalParameters: Parameter args should be final.
[ERROR] src\main\java\com\iluwatar\scheduler\Main.java:[10,38] (coding) MagicNumber: '3' is a magic number.
[ERROR] src\main\java\com\iluwatar\scheduler\Main.java:[10,67] (coding) MagicNumber: '3' is a magic number.
[ERROR] src\main\java\com\iluwatar\scheduler\Main.java:[10,70] (coding) MagicNumber: '4' is a magic number.
[ERROR] src\main\java\com\iluwatar\scheduler\Main.java:[13,62] (coding) MagicNumber: '100' is a magic number.

So I must refactor my code to:

public final class Main {

  /** Task 1 id. */
  private static final int TASK1_ID = 1;

  /** Task 1 priority. */
  private static final int TASK1_PRIORITY = 3;

  /** Task 2 id. */
  private static final int TASK2_ID = 2;

  /** Task 2 priority. */
  private static final int TASK2_PRIORITY = 2;

  /** Task 3 id. */
  private static final int TASK3_ID = 3;

  /** Task 3 priority. */
  private static final int TASK3_PRIORITY = 4;

  /** Simulator delta time. */
  private static final int SIMULATOR_DELTA_TIME = 1;

  /** Simulator end time. */
  private static final int SIMULATOR_END_TIME = 100;

  private Main() {
    // do nothing, just for private constructor
  }

  /**
   * Program entry point.
   *
   * @param args args
   */
  public static void main(final String[] args) {
    Map<Integer, List<Task>> tasks = new HashMap<>();
    Task task1 = new Task(TASK1_ID, TASK1_PRIORITY);
    Task task2 = new Task(TASK2_ID, TASK2_PRIORITY);
    Task task3 = new Task(TASK3_ID, TASK3_PRIORITY);
    tasks.put(0, List.of(task1, task2, task3));

    TaskScheduler scheduler = new FirstComeFirstServedScheduler();
    Simulator simulator = new Simulator(scheduler,
        tasks,
        SIMULATOR_DELTA_TIME,
        SIMULATOR_END_TIME);
    simulator.simulate();
  }
}

I think this code is weird, it's too long and not easy to read.
And I'm not good enough to fix it. So I will close this PR.
Hope you find some better one to help you implement this. Sorry for can not help you.