# ✅ Java TO-DO List Application

Interactive command-line TODO list application built in Java, demonstrating fundamental programming concepts and clean code practices.

## 🚀 Features

- Add tasks with name and description
- Edit existing tasks 
- Delete tasks from list
- Mark tasks as completed
- View all tasks with status indicators
- Input validation with error handling
- User-friendly interface with emojis and clear formatting

## Demo

```
Vítej v aplikaci TO-DO-LIST

=====SEZNAM ÚKOLŮ=====
[○] Nakoupit potraviny – Mléko, chléb, vajíčka
[✓] Dokončit projekt – Java TO-DO aplikace
[○] Zavolat doktorovi – Objednat se na kontrolu

1# Přidat | 2# Upravit | 3# Smazat | 4# Hotovo | 5# Konec
```

## 🛠️ Technologies Used

- **Java 17+** - Core programming language
- **Collections Framework** - ArrayList for task storage
- **Exception Handling** - InputMismatchException, NumberFormatException
- **Object-Oriented Programming** - Classes, encapsulation, methods
- **Input Validation** - Custom validator class with error handling

## Project Structure

```
src/
├── ovadek/todolist/
│   ├── Main.java           # Main application class with UI
│   ├── Task.java           # Task entity with properties
│   └── InputValidator.java # Input validation utilities
```

## 🎯 Key Programming Concepts Demonstrated

- **Object-Oriented Design** - Task class with encapsulation
- **Collections Management** - ArrayList operations (CRUD)
- **Exception Handling** - Try-catch blocks for user input
- **Input Validation** - Custom validator methods
- **String Formatting** - Professional output formatting
- **Method Separation** - Clean, single-responsibility methods

## How to Run

**Clone the repository**
```bash
git clone https://github.com/JinderO/todo-list-java.git
cd todo-list-java
```

**Compile the Java files**
```bash
javac -d bin src/ovadek/todolist/*.java
```

**Run the application**
```bash
java -cp bin ovadek.todolist.Main
```

## What I Learned

- **CRUD Operations** - Create, Read, Update, Delete functionality
- **Input Validation** - Handling edge cases and user errors
- **Collections Framework** - Working with ArrayList and iterations
- **Exception Handling** - Graceful error management
- **Code Organization** - Separating concerns into different classes
- **User Experience** - Creating intuitive command-line interfaces

## Potential Improvements

- Save tasks to file for persistence
- Add due dates and priorities
- Implement task categories
- Add search functionality
- Create GUI version

## Code Highlights

**Clean Input Validation:**
```java
public static int getValidInteger(String prompt, int min, int max) {
    while(true) {
        try {
            int value = Integer.parseInt(scanner.nextLine().trim());
            if (value >= min && value <= max) {
                return value;
            }
        } catch (NumberFormatException e) {
            System.out.println("❌ Zadej platné číslo");
        }
    }
}
```

**Professional toString() Implementation:**
```java
@Override
public String toString() {
    return String.format("[%s] %s – %s", 
        (completed ? "✓" : "○"), name, description);
}
```

## 👨‍💻 Author

**Jindřich Ovádek** - *Java Developer in Training* - [@JinderO](https://github.com/JinderO)

### Technical Achievements

- **Strong OOP Foundation** - Demonstrates solid understanding of object-oriented principles
- **Clean Code Practices** - Readable, well-structured code with proper error handling
- **User-Focused Design** - Intuitive interface with comprehensive input validation
- **CRUD Mastery** - Complete implementation of data manipulation operations
- **Exception Handling** - Professional approach to error management and user feedback

This project showcases **fundamental Java programming skills** including **object-oriented design**, **collections management**, **exception handling**, and **user input validation**. The implementation demonstrates **strong foundational knowledge** essential for **Java developer** positions.