Design patterns to be used in jira

Have discussed about couple of design patterns to be used

1. Factory Pattern

Usage:

To create different types of tasks (Feature, Bug, Story, etc.) based on the user's input.

Implementation:

• TaskFactory: A factory class to create specific task types. This factory determines the type of task and creates the corresponding object.

  public interface Task {
      void displayInfo();
  }
  
  public class FeatureTask implements Task {
      @Override
      public void displayInfo() {
          System.out.println("Feature Task Info");
      }
  }
  
  public class BugTask implements Task {
      @Override
      public void displayInfo() {
          System.out.println("Bug Task Info");
      }
  }
  
  public class TaskFactory {
      public static Task createTask(String type) {
          switch (type) {
              case "Feature":
                  return new FeatureTask();
              case "Bug":
                  return new BugTask();
              default:
                  throw new IllegalArgumentException("Unknown task type: " + type);
          }
      }
  }
  

  2. Observer Pattern

  Usage:

  To allow interested parties (e.g., assignees, project managers) to get notified of changes in task status, assignments, or other updates.

  Implementation:

  • Task as Subject: The Task object maintains a list of observers who are notified of any changes.

  • User as Observer: Users subscribe to specific tasks to receive notifications when the task updates.

    public interface Observer {
        void update(String message);
    }
    
    public class User implements Observer {
        private String name;
    
        public User(String name) {
            this.name = name;
        }
    
        @Override
        public void update(String message) {
            System.out.println("Notification for " + name + ": " + message);
        }
    }
    
    public class Task {
        private List<Observer> observers = new ArrayList<>();
    
        public void addObserver(Observer observer) {
            observers.add(observer);
        }
    
        public void notifyObservers(String message) {
            for (Observer observer : observers) {
                observer.update(message);
            }
        }
    
        public void changeStatus(String newStatus) {
            // logic to change status
            notifyObservers("Status changed to: " + newStatus);
        }
    }
    

  To design a Jira-like task management system, we can use several design patterns to ensure flexibility, modularity, and scalability. Here are some key patterns and where they can be applied in the system:

  ---

  3. State Pattern

  Usage:

  To manage and transition the states of tasks and subtasks, such as Open, In Progress, Completed.

  Implementation:

  • TaskState Interface: Defines behavior for each state.

  • Concrete States (OpenState, InProgressState, etc.): Each state implements TaskState with specific behavior.

  • Task Class: Maintains a reference to a TaskState object and delegates actions to it.

    public interface TaskState {
        void handleRequest();
    }
    
    public class OpenState implements TaskState {
        @Override
        public void handleRequest() {
            System.out.println("Task is now open.");
        }
    }
    
    public class InProgressState implements TaskState {
        @Override
        public void handleRequest() {
            System.out.println("Task is in progress.");
        }
    }
    
    public class Task {
        private TaskState currentState;
    
        public void setState(TaskState state) {
            this.currentState = state;
        }
    
        public void handleRequest() {
            currentState.handleRequest();
        }
    }
    
    

    ---

    4.Singleton Pattern

    Usage:
    

    For a centralized SprintManager or NotificationService to manage sprint-related operations and notifications across the system.

    Implementation:

    • SprintManager and NotificationService: Ensure that only one instance exists and is accessible globally.

      public class SprintManager {
          private static volatile SprintManager instance;
      
          private SprintManager() {}
      
          public static SprintManager getInstance() {
              if (instance == null) {                     // First check (no locking)
                  synchronized (SprintManager.class) {     // Locking only if instance is null
                      if (instance == null) {              // Second check (inside synchronized)
                          instance = new SprintManager();
                      }
                  }
              }
              return instance;
          }
      
          public void manageSprint() {
              // logic to manage sprint
          }
      }
      

  To design a Jira-like task management system, we can use several design patterns to ensure flexibility, modularity, and scalability. Here are some key patterns and where they can be applied in the system:

  ---

  ---

  ---

  ---

  6. Command Pattern

  Usage:

  For actions such as creating tasks, updating statuses, and other operations that can be undone or replayed.

  Implementation:

  • Command Interface: Defines an execute method.

  • Concrete Commands: Implement different actions like CreateTaskCommand, UpdateStatusCommand, etc.

  • Invoker: TaskManager holds and executes commands.

  public interface Command {
      void execute();
  }
  
  public class CreateTaskCommand implements Command {
      private Task task;
  
      public CreateTaskCommand(Task task) {
          this.task = task;
      }
  
      @Override
      public void execute() {
          // logic to create task
      }
  }
  
  public class TaskManager {
      private List<Command> history = new ArrayList<>();
  
      public void executeCommand(Command command) {
          history.add(command);
          command.execute();
      }
  }
  

  ---

  7. Decorator Pattern

  Usage:

  To add additional responsibilities to tasks, such as tracking priority or estimated time without modifying the base Task class.

  Implementation:

  • TaskDecorator: Wraps Task and adds extra features like priority tracking.

    public interface Command {
        void execute();
    }
    
    public class CreateTaskCommand implements Command {
        private Task task;
    
        public CreateTaskCommand(Task task) {
            this.task = task;
        }
    
        @Override
        public void execute() {
            // logic to create task
        }
    }
    
    public class TaskManager {
        private List<Command> history = new ArrayList<>();
    
        public void executeCommand(Command command) {
            history.add(command);
            command.execute();
        }
    }