Comprehensive Project
This lesson is the final project for the Java tutorial, applying all knowledge points.
Project Overview
Build a command-line Todo List application that supports:
- Adding todo items
- Viewing todo list
- Marking as complete
- Deleting todos
- Data persistence (save to file)
- Filtering by status/priority
Data Model
JAVA
import java.io.Serializable;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class Todo implements Serializable {
private static final long serialVersionUID = 1L;
public enum Priority { LOW, MEDIUM, HIGH }
public enum Status { PENDING, COMPLETED }
private int id;
private String title;
private String description;
private Priority priority;
private Status status;
private LocalDateTime createdAt;
private LocalDateTime completedAt;
public Todo(int id, String title, String description, Priority priority) {
this.id = id;
this.title = title;
this.description = description;
this.priority = priority;
this.status = Status.PENDING;
this.createdAt = LocalDateTime.now();
}
// Getters/Setters
public int getId() { return id; }
public String getTitle() { return title; }
public String getDescription() { return description; }
public Priority getPriority() { return priority; }
public Status getStatus() { return status; }
public LocalDateTime getCreatedAt() { return createdAt; }
public LocalDateTime getCompletedAt() { return completedAt; }
public void setStatus(Status status) {
this.status = status;
if (status == Status.COMPLETED) {
this.completedAt = LocalDateTime.now();
}
}
public boolean isCompleted() {
return status == Status.COMPLETED;
}
@Override
public String toString() {
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm");
String statusIcon = isCompleted() ? "✅" : "⬜";
String priorityIcon;
switch (priority) {
case HIGH: priorityIcon = "🔴"; break;
case MEDIUM: priorityIcon = "🟡"; break;
default: priorityIcon = "🟢"; break;
}
return String.format("%s %s [%d] %s (%s)",
statusIcon, priorityIcon, id, title, createdAt.format(formatter));
}
}
Manager Class
JAVA
import java.io.*;
import java.util.*;
import java.util.stream.Collectors;
public class TodoManager {
private List<Todo> todos;
private int nextId;
private static final String FILE_NAME = "todos.dat";
public TodoManager() {
this.todos = new ArrayList<>();
this.nextId = 1;
loadFromFile();
}
// Add todo
public Todo addTodo(String title, String description, Todo.Priority priority) {
Todo todo = new Todo(nextId++, title, description, priority);
todos.add(todo);
saveToFile();
return todo;
}
// Complete todo
public boolean completeTodo(int id) {
Todo todo = findById(id);
if (todo != null && !todo.isCompleted()) {
todo.setStatus(Todo.Status.COMPLETED);
saveToFile();
return true;
}
return false;
}
// Delete todo
public boolean deleteTodo(int id) {
Todo todo = findById(id);
if (todo != null) {
todos.remove(todo);
saveToFile();
return true;
}
return false;
}
// Find todo
public Todo findById(int id) {
return todos.stream()
.filter(t -> t.getId() == id)
.findFirst()
.orElse(null);
}
// Get all todos
public List<Todo> getAllTodos() {
return new ArrayList<>(todos);
}
// Get pending todos
public List<Todo> getPendingTodos() {
return todos.stream()
.filter(t -> !t.isCompleted())
.collect(Collectors.toList());
}
// Get completed todos
public List<Todo> getCompletedTodos() {
return todos.stream()
.filter(Todo::isCompleted)
.collect(Collectors.toList());
}
// Sort by priority
public List<Todo> sortByPriority() {
return todos.stream()
.sorted((a, b) -> {
int cmp = b.getPriority().compareTo(a.getPriority());
return cmp != 0 ? cmp : a.getId() - b.getId();
})
.collect(Collectors.toList());
}
// Sort by creation date
public List<Todo> sortByDate() {
return todos.stream()
.sorted(Comparator.comparing(Todo::getCreatedAt))
.collect(Collectors.toList());
}
// Statistics
public int getTotal() { return todos.size(); }
public int getPendingCount() { return (int) todos.stream().filter(t -> !t.isCompleted()).count(); }
public int getCompletedCount() { return (int) todos.stream().filter(Todo::isCompleted).count(); }
// Save to file
private void saveToFile() {
try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(FILE_NAME))) {
oos.writeObject(todos);
oos.writeInt(nextId);
} catch (IOException e) {
System.out.println("Save failed: " + e.getMessage());
}
}
// Load from file
@SuppressWarnings("unchecked")
private void loadFromFile() {
File file = new File(FILE_NAME);
if (!file.exists()) return;
try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream(FILE_NAME))) {
todos = (List<Todo>) ois.readObject();
nextId = ois.readInt();
} catch (IOException | ClassNotFoundException e) {
System.out.println("Load failed: " + e.getMessage());
}
}
}
Main Program
JAVA
import java.util.List;
import java.util.Scanner;
public class TodoApp {
private static TodoManager manager = new TodoManager();
private static Scanner scanner = new Scanner(System.in);
public static void main(String[] args) {
System.out.println("=== Todo List ===");
int choice;
do {
showMenu();
choice = getIntInput("Enter choice: ");
switch (choice) {
case 1: addTodo(); break;
case 2: listTodos(); break;
case 3: completeTodo(); break;
case 4: deleteTodo(); break;
case 5: showStatistics(); break;
case 6: listByPriority(); break;
case 0: System.out.println("Goodbye!"); break;
default: System.out.println("Invalid choice");
}
} while (choice != 0);
scanner.close();
}
private static void showMenu() {
System.out.println("\n--- Menu ---");
System.out.println("1. Add todo");
System.out.println("2. View all todos");
System.out.println("3. Mark complete");
System.out.println("4. Delete todo");
System.out.println("5. Statistics");
System.out.println("6. Sort by priority");
System.out.println("0. Exit");
}
private static void addTodo() {
System.out.print("Title: ");
String title = scanner.nextLine().trim();
if (title.isEmpty()) {
System.out.println("Title cannot be empty");
return;
}
System.out.print("Description: ");
String desc = scanner.nextLine().trim();
System.out.println("Priority: 1-Low 2-Medium 3-High");
int p = getIntInput("Choice: ");
Todo.Priority priority;
switch (p) {
case 1: priority = Todo.Priority.LOW; break;
case 3: priority = Todo.Priority.HIGH; break;
default: priority = Todo.Priority.MEDIUM;
}
Todo todo = manager.addTodo(title, desc, priority);
System.out.println("Added: " + todo);
}
private static void listTodos() {
List<Todo> todos = manager.getAllTodos();
if (todos.isEmpty()) {
System.out.println("No todos found");
return;
}
System.out.println("\n--- Todo List ---");
for (Todo todo : todos) {
System.out.println(todo);
}
System.out.printf("Total: %d (Pending: %d, Completed: %d)%n",
manager.getTotal(), manager.getPendingCount(), manager.getCompletedCount());
}
private static void completeTodo() {
listTodos();
int id = getIntInput("Enter ID to complete: ");
if (manager.completeTodo(id)) {
System.out.println("Marked as complete");
} else {
System.out.println("Invalid ID or already completed");
}
}
private static void deleteTodo() {
listTodos();
int id = getIntInput("Enter ID to delete: ");
if (manager.deleteTodo(id)) {
System.out.println("Deleted");
} else {
System.out.println("Invalid ID");
}
}
private static void showStatistics() {
System.out.println("\n=== Statistics ===");
System.out.println("Total: " + manager.getTotal());
System.out.println("Pending: " + manager.getPendingCount());
System.out.println("Completed: " + manager.getCompletedCount());
double rate = manager.getTotal() > 0 ?
(double) manager.getCompletedCount() / manager.getTotal() * 100 : 0;
System.out.printf("Completion rate: %.1f%%%n", rate);
}
private static void listByPriority() {
List<Todo> todos = manager.sortByPriority();
System.out.println("\n--- Sorted by Priority ---");
for (Todo todo : todos) {
System.out.println(todo);
}
}
private static int getIntInput(String prompt) {
System.out.print(prompt);
while (!scanner.hasNextInt()) {
System.out.print("Please enter a number: ");
scanner.next();
}
int value = scanner.nextInt();
scanner.nextLine(); // Consume newline
return value;
}
}
Example Output
TEXT
=== Todo List ===
--- Menu ---
1. Add todo
2. View all todos
3. Mark complete
4. Delete todo
5. Statistics
6. Sort by priority
0. Exit
Enter choice: 1
Title: Learn Java
Description: Complete Java tutorial lesson 32
Priority: 1-Low 2-Medium 3-High
Choice: 3
Added: ⬜ 🔴 [1] Learn Java (2026-06-24 14:30)
Enter choice: 2
--- Todo List ---
⬜ 🔴 [1] Learn Java (2026-06-24 14:30)
Total: 1 (Pending: 1, Completed: 0)
Knowledge Summary
| Knowledge | Application |
|---|---|
| Classes & Objects | Todo, TodoManager class design |
| Encapsulation | Private attributes, getters/setters |
| Enums | Priority, Status enums |
| Collections | List for todos, Stream operations |
| Exception handling | File IO exception handling |
| File IO | Serialization for save/load |
| Date/Time | LocalDateTime for timestamps |
| Lambda | Stream sorting, filtering |
| Generics | List |
Extended Features
1. Filter by Date
JAVA
public List<Todo> getTodayTodos() {
LocalDate today = LocalDate.now();
return todos.stream()
.filter(t -> t.getCreatedAt().toLocalDate().equals(today))
.collect(Collectors.toList());
}
2. Search Function
JAVA
public List<Todo> search(String keyword) {
String lower = keyword.toLowerCase();
return todos.stream()
.filter(t -> t.getTitle().toLowerCase().contains(lower) ||
t.getDescription().toLowerCase().contains(lower))
.collect(Collectors.toList());
}
3. Export to Text
JAVA
public void exportToText(String filename) throws IOException {
try (PrintWriter writer = new PrintWriter(new FileWriter(filename))) {
writer.println("=== Todo List Export ===");
writer.println("Export time: " + LocalDateTime.now());
writer.println();
for (Todo todo : todos) {
writer.println(todo);
if (!todo.getDescription().isEmpty()) {
writer.println(" " + todo.getDescription());
}
writer.println();
}
}
}
❓ Frequently Asked Questions
Q How to extend to a GUI application?
A Use JavaFX or Swing to implement a graphical interface.
Q How to support multiple users?
A Each user gets their own data file, or use database storage.
Q How to add reminder functionality?
A Use Timer/ScheduledExecutorService to check for due tasks.
📖 Summary
- Apply classes, collections, exceptions, IO, Lambda knowledge together
- Data persistence using serialization
- Stream API simplifies collection operations
- Enums define fixed constants
📝 Exercises
- Extend functionality: Add search and date filtering
- Data export: Support exporting to CSV format
- GUI version: Implement graphical interface with JavaFX
🎉 Congratulations on Completing the Java Tutorial!
Through 32 lessons, you have mastered:
- Java basic syntax
- Object-oriented programming
- Collection framework
- Exception handling
- File IO
- Regular expressions and JSON processing
Next steps to continue learning:
- Spring Boot framework
- Database programming (JDBC/MyBatis)
- Web development
- Design patterns