Todo List TUI in Java

1cd Site/static/code/examples/java
2javac TodoCli.java
3java TodoCli

  1import java.io.IOException;
  2import java.nio.file.Files;
  3import java.nio.file.Path;
  4import java.util.ArrayList;
  5import java.util.List;
  6import java.util.Locale;
  7import java.util.Scanner;
  8
  9public class TodoCli {
 10    public static void main(String[] args) {
 11        Path saveFile = Path.of("todo-java.txt");
 12        Store store = new Store(saveFile);
 13        store.load();
 14
 15        Scanner scanner = new Scanner(System.in);
 16        System.out.println("Commands: add, list, done, remove, quit");
 17
 18        while (true) {
 19            System.out.print("> ");
 20            String command = scanner.nextLine().trim().toLowerCase(Locale.ROOT);
 21
 22            switch (command) {
 23                case "add":
 24                    System.out.print("Task: ");
 25                    String text = scanner.nextLine().trim();
 26                    if (!text.isEmpty()) {
 27                        store.add(text);
 28                        store.save();
 29                    }
 30                    break;
 31                case "list":
 32                    store.print();
 33                    break;
 34                case "done":
 35                    System.out.print("Task id: ");
 36                    int doneId = parseId(scanner.nextLine());
 37                    if (store.markDone(doneId)) {
 38                        store.save();
 39                    }
 40                    break;
 41                case "remove":
 42                    System.out.print("Task id: ");
 43                    int removeId = parseId(scanner.nextLine());
 44                    if (store.remove(removeId)) {
 45                        store.save();
 46                    }
 47                    break;
 48                case "quit":
 49                    System.out.println("Saved to " + saveFile);
 50                    return;
 51                default:
 52                    System.out.println("Use: add, list, done, remove, quit");
 53            }
 54        }
 55    }
 56
 57    private static int parseId(String raw) {
 58        try {
 59            return Integer.parseInt(raw.trim());
 60        } catch (NumberFormatException e) {
 61            return -1;
 62        }
 63    }
 64
 65    private static class Store {
 66        private final Path saveFile;
 67        private final List<Task> tasks = new ArrayList<>();
 68        private int nextId = 1;
 69
 70        private Store(Path saveFile) {
 71            this.saveFile = saveFile;
 72        }
 73
 74        private void add(String text) {
 75            tasks.add(new Task(nextId++, text, false));
 76            System.out.println("Added.");
 77        }
 78
 79        private boolean markDone(int id) {
 80            for (Task task : tasks) {
 81                if (task.id == id) {
 82                    task.done = true;
 83                    System.out.println("Marked done.");
 84                    return true;
 85                }
 86            }
 87            System.out.println("Task not found.");
 88            return false;
 89        }
 90
 91        private boolean remove(int id) {
 92            boolean removed = tasks.removeIf(task -> task.id == id);
 93            System.out.println(removed ? "Removed." : "Task not found.");
 94            return removed;
 95        }
 96
 97        private void print() {
 98            if (tasks.isEmpty()) {
 99                System.out.println("No tasks yet.");
100                return;
101            }
102            for (Task task : tasks) {
103                String box = task.done ? "[x]" : "[ ]";
104                System.out.println(task.id + ". " + box + " " + task.text);
105            }
106        }
107
108        private void load() {
109            if (!Files.exists(saveFile)) {
110                return;
111            }
112            try {
113                for (String line : Files.readAllLines(saveFile)) {
114                    String[] parts = line.split("\\|", 3);
115                    if (parts.length < 3) {
116                        continue;
117                    }
118                    int id = Integer.parseInt(parts[0]);
119                    boolean done = Boolean.parseBoolean(parts[1]);
120                    String text = parts[2];
121                    tasks.add(new Task(id, text, done));
122                    nextId = Math.max(nextId, id + 1);
123                }
124            } catch (IOException | NumberFormatException e) {
125                System.out.println("Starting with empty list.");
126                tasks.clear();
127                nextId = 1;
128            }
129        }
130
131        private void save() {
132            List<String> lines = new ArrayList<>();
133            for (Task task : tasks) {
134                lines.add(task.id + "|" + task.done + "|" + task.text);
135            }
136            try {
137                Files.write(saveFile, lines);
138            } catch (IOException e) {
139                System.out.println("Could not save tasks.");
140            }
141        }
142    }
143
144    private static class Task {
145        private final int id;
146        private final String text;
147        private boolean done;
148
149        private Task(int id, String text, boolean done) {
150            this.id = id;
151            this.text = text;
152            this.done = done;
153        }
154    }
155}

1javac TodoCli.java
2java TodoCli