Note: To do this project, you can go to https://roadmap.sh/projects/task-tracker.

A Java-based command line interface (CLI) task tracker that helps you manage your tasks efficiently. The project demonstrates practical implementation of file handling, JSON manipulation, and command-line argument processing.

The application runs from the command line and stores tasks in a JSON file. Features include:

• Add, Update, and Delete tasks
• Mark tasks as in progress or done
• List all tasks
• List tasks by status (done, todo, in-progress)

• You can use any programming language to build this project.
• Use positional arguments in command line to accept user inputs.
• Use a JSON file to store the tasks in the current directory.
• The JSON file should be created if it does not exist.
• Use the native file system module of your programming language to interact with the JSON file.
• Do not use any external libraries or frameworks to build this project.
• Ensure to handle errors and edge cases gracefully.

1. Task Class

   • Properties: id, description, status, createdAt, updatedAt
   • Uses Java's LocalDate for date handling
   • Custom JSON serialization/deserialization methods

2. TaskManager Class

   • Handles all file operations using RandomAccessFile
   • Implements CRUD operations for tasks
   • Uses regex for JSON parsing
   • Stream API for task filtering and manipulation

1. Reading Tasks

   • Uses RandomAccessFile in read mode
   • Reads entire file content as bytes
   • Parses JSON objects using regex pattern matching
   • Converts JSON strings to Task objects

2. Writing Tasks

   • Uses RandomAccessFile in read-write mode
   • Maintains JSON array structure
   • Special handling for empty files
   • Efficient append operations

3. Updating Tasks

   • Reads all tasks into memory
   • Updates specific task
   • Rewrites entire file with updated content

# Adding a new task
task-cli add "Buy groceries"

# Updating a task
task-cli update 1 "Buy groceries and cook dinner"

# Deleting a task
task-cli delete 1

# Marking task status
task-cli mark-in-progress 1
task-cli mark-done 1

# Listing tasks
task-cli list
task-cli list done
task-cli list todo
task-cli list in-progress

public class Task {
    Integer id;
    String description;
    TaskStatus status;
    LocalDate createdAt, updatedAt;
    // Methods for JSON conversion and property access
}

1. Adding Tasks:

   RandomAccessFile file = new RandomAccessFile(fileName, "rw");
   if(file.read() == -1) {
       file.write("[".getBytes());
       file.write(taskJson.getBytes());
       file.write("]".getBytes());
   } else {
       file.seek(file.length() - 1);
       file.write(",".getBytes());
       file.write(taskJson.getBytes());
       file.write("]".getBytes());
   }

2. Task Management:

   • Uses ArrayList for in-memory task manipulation
   • Stream API for filtering and updating tasks
   • Regular expressions for parsing JSON elements

• Input validation for command-line arguments
• File operation error handling with try-catch blocks
• Task existence verification before updates